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Sample records for platelet release reaction

  1. Endobrevin/VAMP-8 is the primary v-SNARE for the platelet release reaction.

    Science.gov (United States)

    Ren, Qiansheng; Barber, Holly Kalani; Crawford, Garland L; Karim, Zubair A; Zhao, Chunxia; Choi, Wangsun; Wang, Cheng-Chun; Hong, Wanjin; Whiteheart, Sidney W

    2007-01-01

    Platelet secretion is critical to hemostasis. Release of granular cargo is mediated by soluble NSF attachment protein receptors (SNAREs), but despite consensus on t-SNAREs usage, it is unclear which Vesicle Associated Membrane Protein (VAMPs: synaptobrevin/VAMP-2, cellubrevin/VAMP-3, TI-VAMP/VAMP-7, and endobrevin/VAMP-8) is required. We demonstrate that VAMP-8 is required for release from dense core granules, alpha granules, and lysosomes. Platelets from VAMP-8-/- mice have a significant defect in agonist-induced secretion, though signaling, morphology, and cargo levels appear normal. In contrast, VAMP-2+/-, VAMP-3-/-, and VAMP-2+/-/VAMP-3-/- platelets showed no defect. Consistently, tetanus toxin had no effect on secretion from permeabilized mouse VAMP-3-/- platelets or human platelets, despite cleavage of VAMP-2 and/or -3. Tetanus toxin does block the residual release from permeabilized VAMP-8-/- platelets, suggesting a secondary role for VAMP-2 and/or -3. These data imply a ranked redundancy of v-SNARE usage in platelets and suggest that VAMP-8-/- mice will be a useful in vivo model to study platelet exocytosis in hemostasis and vascular inflammation.

  2. Granule stores from cellubrevin/VAMP-3 null mouse platelets exhibit normal stimulus-induced release.

    Science.gov (United States)

    Schraw, Todd D; Rutledge, Tara W; Crawford, Garland L; Bernstein, Audrey M; Kalen, Amanda L; Pessin, Jeffery E; Whiteheart, Sidney W

    2003-09-01

    It is widely accepted that the platelet release reaction is mediated by heterotrimeric complexes of integral membrane proteins known as SNAREs (SNAP receptors). In an effort to define the precise molecular machinery required for platelet exocytosis, we have analyzed platelets from cellubrevin/VAMP-3 knockout mice. Cellubrevin/VAMP-3 has been proposed to be a critical v-SNARE for human platelet exocytosis; however, data reported here suggest that it is not required for platelet function. Upon stimulation with increasing concentrations of thrombin, collagen, or with thrombin for increasing time there were no differences in secretion of [3H]-5HT (dense core granules), platelet factor IV (alpha granules), or hexosaminidase (lysosomes) between null and wild-type platelets. There were no gross differences in bleeding times nor in agonist-induced aggregation measured in platelet-rich plasma or with washed platelets. Western blotting of wild-type, heterozygous, and null platelets confirmed the lack of cellubrevin/VAMP-3 in nulls and showed that most elements of the secretion machinery are expressed at similar levels. While the secretory machinery in mice was similar to humans, mice did express apparently higher levels of synaptobrevin/VAMP-2. These data show that the v-SNARE, cellubrevin/VAMP-3 is not a requirement for the platelet release reaction in mice.

  3. Decreased TGF-β1 and VEGF Release in Cystic Fibrosis Platelets: Further Evidence for Platelet Defects in Cystic Fibrosis

    Science.gov (United States)

    Maloney, James P.; Narasimhan, Jayashree; Biller, Julie

    2016-01-01

    Purpose Cystic fibrosis (CF) patients suffer from chronic lung inflammation. This inflammation may activate platelets. There are limited data on the role of platelet-secreted cytokines in CF. Platelet cytokines with inflammatory effects include vascular endothelial growth factor (VEGF) and transforming growth factor-β1 (TGF-β1). As levels of these cytokines are tenfold greater in serum than plasma due to platelet release, serum levels may be one index of platelet content; but a more specific index is release during the aggregation of isolated platelets. We postulated that altered release of these platelet cytokines occurs in CF. Methods We obtained sera and plasma from CF outpatients (n=21) and from healthy controls (n=20), measured VEGF and TGF-β1, assessed for correlations with platelet number, analyzed cytokine release during platelet aggregation to collagen, and analyzed differences in maximal platelet aggregation. Results Platelet number and maximal aggregation levels were higher in CF. Plasma and serum levels of TGF-β1 and VEGF were higher in CF, but these levels were similar after adjusting for platelet number (serum cytokines correlated with platelet count). The release of VEGF and TGF-β1 during aggregation was decreased in CF platelets (by 52% and 29%, respectively). Conclusion Platelet release is not a source of the elevated blood proinflammatory cytokines TGF-β1 and VEGF in CF, as platelets from CF patients actually release less of these cytokines. These data provide further evidence for platelet defects in CF. PMID:27423781

  4. Platelet-rich plasma preparation using three devices : Implications for platelet activation and platelet growth factor release

    NARCIS (Netherlands)

    Everts, Peter A. M.; Mahoney, Christine Brown; Hoffmann, Johannes J. M. L.; Schonberger, Jacques P. A. M.; Box, Henk A. M.; Van Zundert, Andre; Knape, Johannes T. A.

    2006-01-01

    Background: In this study, three commercial systems for the preparation of platelet-rich plasma (PRP) were compared and platelet growth factors release was measured. Methods: Ten healthy volunteers donated whole blood that was fractionated by a blood cell separator, and a table-top centrifuge to pre

  5. Effects of heparin on platelet aggregation and release and thromboxane A2 production

    Energy Technology Data Exchange (ETDEWEB)

    Mohammad, S.F.; Anderson, W.H.; Smith, J.B.; Chuang, H.Y.; Mason, R.G.

    1981-08-01

    Heparin, when added to citrated platelet-rich plasma (PRP), caused potentiation of platelet aggregation and the release reaction induced by the aggregating agents adenosine diphosphate (ADP), arachidonic acid, collagen, and epinephrine. At low concentrations (4.7 x 10(-5) M) arachidonic acid failed to cause aggregation of platelets in citrated PRP. However, in the presence of heparin, the same concentration of arachidonic acid caused aggregation. Examination of PRP for the presence of thromboxane A2 (TxA2) by use of a bioassay revealed that heparin also stimulated release of TxA2. This finding indicated that platelets released more TxA2 when they were challenged by low concentrations of arachidonic acid in the presence of heparin than in its absence. Platelets were labeled with /sup 3/H-arachidonic acid and /sup 14/C-serotonin, and attempts were made to determine whether heparin stimulated the platelet release reaction first with subsequent increased production of TxA2, or alternatively, whether heparin stimulated TxA2 production first with subsequent enhancement of the release reaction. In view of the demonstrated simultaneous release of /sup 14/C-serotonin and /sup 3/H-arachidonic acid metabolites, it appeared that either release of /sup 14/C and /sup 3/H occurs concurrently or, even if one of these events is dependent on the other, both events take place in rapid succession. Timed sequential studies revealed that in the presence of arachidonic acid, the addition of heparin hastened the apparently simultaneous release of both /sup 14/C and /sup 3/H.

  6. Platelet reactions to modified surfaces under dynamic conditions.

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    Rhodes, N P; Shortland, A P; Rattray, A; Williams, D F

    1998-12-01

    The influence of surfaces on the reactions of platelets in whole blood under laminar flow was investigated in a cone and plate viscometer. Citrated whole blood was exposed to steel, PMMA and PMMA modified with PEO at low (500 s(-1)) and high (4000 s(-1)) wall shear rates at room temperature for a period of 100 s. Treated blood samples were fixed with paraformaldehyde, stained with a monoclonal antibody for CD41 (platelet GPIIb/IIIa) conjugated with phycoerythrin and analyzed by flow cytometry. The reactions of platelets (microparticle generation and formation of platelet-platelet, platelet-red blood cell and red blood cell-microparticle aggregates) to these environments were quantified. Additionally, the size of platelet-platelet aggregates was assessed. The percentage platelet aggregation and numbers of microparticles generated were independent of surface type at any shear rate. The composition of the aggregates formed was influenced by the surface: at low and high shear rates PMMA caused the generation of platelet-platelet aggregates of the greatest size. The numbers of red blood cell-platelet and red blood cell-microparticle aggregates also varied depending on the surface. Fewer red blood cell-platelet aggregates were formed at higher shear rates, whereas the reverse was true for red blood cell-microparticle aggregates. It is concluded that these variations may help to explain the differential effects of surfaces to the induction of distant thrombotic events: microparticles may be protected from loss from the blood stream by their association with red blood cells at high shear rates.

  7. Platelets release mitochondria serving as substrate for bactericidal group IIA-secreted phospholipase A2 to promote inflammation

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    Boudreau, Luc H.; Duchez, Anne-Claire; Cloutier, Nathalie; Soulet, Denis; Martin, Nicolas; Bollinger, James; Paré, Alexandre; Rousseau, Matthieu; Naika, Gajendra S.; Lévesque, Tania; Laflamme, Cynthia; Marcoux, Geneviève; Lambeau, Gérard; Farndale, Richard W.; Pouliot, Marc; Hamzeh-Cognasse, Hind; Cognasse, Fabrice; Garraud, Olivier; Nigrovic, Peter A.; Guderley, Helga; Lacroix, Steve; Thibault, Louis; Semple, John W.; Gelb, Michael H.

    2014-01-01

    Mitochondrial DNA (mtDNA) is a highly potent inflammatory trigger and is reportedly found outside the cells in blood in various pathologies. Platelets are abundant in blood where they promote hemostasis. Although lacking a nucleus, platelets contain functional mitochondria. On activation, platelets produce extracellular vesicles known as microparticles. We hypothesized that activated platelets could also release their mitochondria. We show that activated platelets release respiratory-competent mitochondria, both within membrane-encapsulated microparticles and as free organelles. Extracellular mitochondria are found in platelet concentrates used for transfusion and are present at higher levels in those that induced acute reactions (febrile nonhemolytic reactions, skin manifestations, and cardiovascular events) in transfused patients. We establish that the mitochondrion is an endogenous substrate of secreted phospholipase A2 IIA (sPLA2-IIA), a phospholipase otherwise specific for bacteria, likely reflecting the ancestral proteobacteria origin of mitochondria. The hydrolysis of the mitochondrial membrane by sPLA2-IIA yields inflammatory mediators (ie, lysophospholipids, fatty acids, and mtDNA) that promote leukocyte activation. Two-photon microscopy in live transfused animals revealed that extracellular mitochondria interact with neutrophils in vivo, triggering neutrophil adhesion to the endothelial wall. Our findings identify extracellular mitochondria, produced by platelets, at the midpoint of a potent mechanism leading to inflammatory responses. PMID:25082876

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

    Energy Technology Data Exchange (ETDEWEB)

    Laduca, F.M.; Bell, W.R.; Bettigole, R.E. (Johns Hopkins Univ. School of Medicine, Baltimore, MD (USA) State Univ. of New York, Buffalo (USA))

    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.

  9. Platelet-rich plasma releasate differently stimulates cellular commitment toward the chondrogenic lineage according to concentration

    OpenAIRE

    Ronaldo JFC do Amaral; Amos Matsiko; Marcel RP Tomazette; Wanessa KR Rocha; Eric Cordeiro-Spinetti; Levingstone, Tanya J; Marcos Farina; O’Brien, Fergal J.; EL-CHEIKH, MARCIA C.; Alex Balduino

    2015-01-01

    Platelet-rich plasma has been used to treat articular cartilage defects, with the expectations of anabolic and anti-inflammatory effects. However, its role on cellular chondrogenic or fibrogenic commitment is still a controversy. Herein, the role of platelet-rich plasma releasate, the product obtained following platelet-rich plasma activation, on cellular commitment toward the chondrogenic lineage was evaluated in vitr...

  10. Platelet-rich plasma stimulated by pulse electric fields: Platelet activation, procoagulant markers, growth factor release and cell proliferation.

    Science.gov (United States)

    Frelinger, A L; Torres, A S; Caiafa, A; Morton, C A; Berny-Lang, M A; Gerrits, A J; Carmichael, S L; Neculaes, V B; Michelson, A D

    2016-01-01

    Therapeutic use of activated platelet-rich plasma (PRP) has been explored for wound healing, hemostasis and antimicrobial wound applications. Pulse electric field (PEF) stimulation may provide more consistent platelet activation and avoid complications associated with the addition of bovine thrombin, the current state of the art ex vivo activator of therapeutic PRP. The aim of this study was to compare the ability of PEF, bovine thrombin and thrombin receptor activating peptide (TRAP) to activate human PRP, release growth factors and induce cell proliferation in vitro. Human PRP was prepared in the Harvest SmartPreP2 System and treated with vehicle, PEF, bovine thrombin, TRAP or Triton X-100. Platelet activation and procoagulant markers and microparticle generation were measured by flow cytometry. Released growth factors were measured by ELISA. The releasates were tested for their ability to stimulate proliferation of human epithelial cells in culture. PEF produced more platelet-derived microparticles, P-selectin-positive particles and procoagulant annexin V-positive particles than bovine thrombin or TRAP. These differences were associated with higher levels of released epidermal growth factor after PEF than after bovine thrombin or TRAP but similar levels of platelet-derived, vascular-endothelial, and basic fibroblast growth factors, and platelet factor 4. Supernatant from PEF-treated platelets significantly increased cell proliferation compared to plasma. In conclusion, PEF treatment of fresh PRP results in generation of microparticles, exposure of prothrombotic platelet surfaces, differential release of growth factors compared to bovine thrombin and TRAP and significant cell proliferation. These results, together with PEF's inherent advantages, suggest that PEF may be a superior alternative to bovine thrombin activation of PRP for therapeutic applications.

  11. Platelet-rich plasma releasate differently stimulates cellular commitment toward the chondrogenic lineage according to concentration

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    Ronaldo JFC do Amaral

    2015-07-01

    Full Text Available Platelet-rich plasma has been used to treat articular cartilage defects, with the expectations of anabolic and anti-inflammatory effects. However, its role on cellular chondrogenic or fibrogenic commitment is still a controversy. Herein, the role of platelet-rich plasma releasate, the product obtained following platelet-rich plasma activation, on cellular commitment toward the chondrogenic lineage was evaluated in vitro. Human nasoseptal chondrogenic cells and human bone marrow mesenchymal stromal cells were used as cell types already committed to the chondrogenic lineage and undifferentiated cells, respectively, as different concentrations of platelet-rich plasma releasate were tested in comparison to commonly used fetal bovine serum. Low concentration of platelet-rich plasma releasate (2.5% presented similar effects on cellular growth compared to 10% fetal bovine serum, for both cell types. In a three-dimensional culture system, platelet-rich plasma releasate alone did not induce full nasoseptal chondrogenic cells cartilage-like pellet formation. Nonetheless, platelet-rich plasma releasate played a significant role on cell commitment as high-passage nasoseptal chondrogenic cells only originated cartilage-like pellets when expanded in the presence of platelet-rich plasma releasate rather than fetal bovine serum. Histological analyses and measurements of pellet area demonstrated that even low concentrations of platelet-rich plasma releasate were enough to prevent nasoseptal chondrogenic cells from losing their chondrogenic potential due to in vitro expansion thereby promoting their recommitment. Low concentration of platelet-rich plasma releasate supplemented in chondrogenic medium also increased the chondrogenic potential of mesenchymal stromal cells seeded on collagen-hyaluronic acid scaffolds, as observed by an increase in chondrogenic-related gene expression, sulfated glycosaminoglycan production, and compressive modulus following in vitro

  12. Platelet-rich plasma releasate differently stimulates cellular commitment toward the chondrogenic lineage according to concentration

    Science.gov (United States)

    Matsiko, Amos; Tomazette, Marcel RP; Rocha, Wanessa KR; Cordeiro-Spinetti, Eric; Levingstone, Tanya J; Farina, Marcos; O’Brien, Fergal J; El-Cheikh, Marcia C; Balduino, Alex

    2015-01-01

    Platelet-rich plasma has been used to treat articular cartilage defects, with the expectations of anabolic and anti-inflammatory effects. However, its role on cellular chondrogenic or fibrogenic commitment is still a controversy. Herein, the role of platelet-rich plasma releasate, the product obtained following platelet-rich plasma activation, on cellular commitment toward the chondrogenic lineage was evaluated in vitro. Human nasoseptal chondrogenic cells and human bone marrow mesenchymal stromal cells were used as cell types already committed to the chondrogenic lineage and undifferentiated cells, respectively, as different concentrations of platelet-rich plasma releasate were tested in comparison to commonly used fetal bovine serum. Low concentration of platelet-rich plasma releasate (2.5%) presented similar effects on cellular growth compared to 10% fetal bovine serum, for both cell types. In a three-dimensional culture system, platelet-rich plasma releasate alone did not induce full nasoseptal chondrogenic cells cartilage-like pellet formation. Nonetheless, platelet-rich plasma releasate played a significant role on cell commitment as high-passage nasoseptal chondrogenic cells only originated cartilage-like pellets when expanded in the presence of platelet-rich plasma releasate rather than fetal bovine serum. Histological analyses and measurements of pellet area demonstrated that even low concentrations of platelet-rich plasma releasate were enough to prevent nasoseptal chondrogenic cells from losing their chondrogenic potential due to in vitro expansion thereby promoting their recommitment. Low concentration of platelet-rich plasma releasate supplemented in chondrogenic medium also increased the chondrogenic potential of mesenchymal stromal cells seeded on collagen-hyaluronic acid scaffolds, as observed by an increase in chondrogenic-related gene expression, sulfated glycosaminoglycan production, and compressive modulus following in vitro culture. On the

  13. The effect of platelet releasate on wound healing in animal models.

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    Ksander, G A; Sawamura, S J; Ogawa, Y; Sundsmo, J; McPherson, J M

    1990-05-01

    The alpha granules of platelets contain growth factors that are important in wound healing. We found that a major effect of thrombin-induced human platelet releasates in animal models of wound healing is to enhance the development of granulation tissue and new connective tissue matrix. These studies provide further evidence that platelet-derived protein factors may be useful in treating full-thickness dermal wounds by increasing the rate of granulation tissue formation.

  14. Platelet-Released Growth Factors Induce Differentiation of Primary Keratinocytes

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    Andreas Bayer

    2017-01-01

    Full Text Available Autologous thrombocyte concentrate lysates, for example, platelet-released growth factors, (PRGFs or their clinically related formulations (e.g., Vivostat PRF® came recently into the physicians’ focus as they revealed promising effects in regenerative and reparative medicine such as the support of healing of chronic wounds. To elucidate the underlying mechanisms, we analyzed the influence of PRGF and Vivostat PRF on human keratinocyte differentiation in vitro and on epidermal differentiation status of skin wounds in vivo. Therefore, we investigated the expression of early (keratin 1 and keratin 10 and late (transglutaminase-1 and involucrin differentiation markers. PRGF treatment of primary human keratinocytes decreased keratin 1 and keratin 10 gene expression but induced involucrin and transglutaminase-1 gene expression in an epidermal growth factor receptor- (EGFR- dependent manner. In concordance with these results, microscopic analyses revealed that PRGF-treated human keratinocytes displayed morphological features typical of keratinocytes undergoing terminal differentiation. In vivo treatment of artificial human wounds with Vivostat PRF revealed a significant induction of involucrin and transglutaminase-1 gene expression. Together, our results indicate that PRGF and Vivostat PRF induce terminal differentiation of primary human keratinocytes. This potential mechanism may contribute to the observed beneficial effects in the treatment of hard-to-heal wounds with autologous thrombocyte concentrate lysates in vivo.

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

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    Daniela eWeth

    2015-04-01

    Full Text Available 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, neutralisation 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.

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

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

    2016-07-01

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

  17. Studies on the biological effects of ozone: 10. Release of factors from ozonated human platelets.

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    Valacchi, G; Bocci, V

    1999-01-01

    In a previous work we have shown that heparin, in the presence of ozone (O3), promotes a dose-dependent platelet aggregation, while after Ca2+ chelation with citrate, platelet aggregation is almost negligible. These results led us to think that aggregation may enhance the release of platelet components. We have here shown that indeed significantly higher amount of platelet-derived growth factor (PDGF), transforming growth factor beta1 (TGF-beta1) and interleukin-8 (IL-8) are released in a dose-dependent manner after ozonation of heparinised platelet-rich plasma samples. These findings may explain the enhanced healing of torpid ulcers in patients with chronic limb ischemia treated with O3 autohaemoteraphy (O3-AHT).

  18. Studies on the Biological Effects of Ozone: 10. Release of Factors from Ozonated Human Platelets

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    G. Valacchi

    1999-01-01

    Full Text Available In a previous work we have shown that heparin, in the presence of ozone (O3, promotes a dose-dependent platelet aggregation, while after Ca2+ chelation with citrate, platelet aggregation is almost negligible. These results led us to think that aggregation may enhance the release of platelet components. We have here shown that indeed significantly higher amount of platelet-derived growth factor (PDGF, transforming growth factor β1 (TGF-β1 and interleukin-8(IL-8 are released in a dose-dependent manner after ozonation of heparinised platelet-rich plasma samples. These findings may explain the enhanced healing of torpid ulcers in patients with chronic limbischemia treated with O3 autohaemoteraphy (O3-AHT.

  19. Control of angiogenesis by galectins involves the release of platelet-derived proangiogenic factors.

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    Julia Etulain

    Full Text Available Platelets contribute to vessel formation through the release of angiogenesis-modulating factors stored in their α-granules. Galectins, a family of lectins that bind β-galactoside residues, are up-regulated in inflammatory and cancerous tissues, trigger platelet activation and mediate vascularization processes. Here we aimed to elucidate whether the release of platelet-derived proangiogenic molecules could represent an alternative mechanism through which galectins promote neovascularization. We show that different members of the galectin family can selectively regulate the release of angiogenic molecules by human platelets. Whereas Galectin (Gal-1, -3, and -8 triggered vascular endothelial growth factor (VEGF release, only Gal-8 induced endostatin secretion. Release of VEGF induced by Gal-8 was partially prevented by COX-1, PKC, p38 and Src kinases inhibitors, whereas Gal-1-induced VEGF secretion was inhibited by PKC and ERK blockade, and Gal-3 triggered VEGF release selectively through a PKC-dependent pathway. Regarding endostatin, Gal-8 failed to stimulate its release in the presence of PKC, Src and ERK inhibitors, whereas aspirin or p38 inhibitor had no effect on endostatin release. Despite VEGF or endostatin secretion, platelet releasates generated by stimulation with each galectin stimulated angiogenic responses in vitro including endothelial cell proliferation and tubulogenesis. The platelet angiogenic activity was independent of VEGF and was attributed to the concerted action of other proangiogenic molecules distinctly released by each galectin. Thus, secretion of platelet-derived angiogenic molecules may represent an alternative mechanism by which galectins promote angiogenic responses and its selective blockade may lead to the development of therapeutic strategies for angiogenesis-related diseases.

  20. Influence of storage conditions on the release of growth factors in platelet-rich blood derivatives

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    Düregger Katharina

    2016-09-01

    Full Text Available Thrombocytes can be concentrated in blood derivatives and used as autologous transplants e.g. for wound treatment due to the release of growth factors such as platelet derived growth factor (PDGF. Conditions for processing and storage of these platelet-rich blood derivatives influence the release of PDGF from the platelet-bound α-granules into the plasma. In this study Platelet rich plasma (PRP and Platelet concentrate (PC were produced with a fully automated centrifugation system. Storage of PRP and PC for 1 h up to 4 months at temperatures between −20°C and +37°C was applied with the aim of evaluating the influence on the amount of released PDGF. Storage at −20°C resulted in the highest release of PDGF in PRP and a time dependency was determined: prolonged storage up to 1 month in PRP and 10 days in PC increased the release of PDGF. Regardless of the storage conditions, the release of PDGF per platelet was higher in PC than in PRP.

  1. Angiotensin II AT1 receptor antagonists inhibit platelet adhesion and aggregation by nitric oxide release.

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    Kalinowski, Leszek; Matys, Tomasz; Chabielska, Ewa; Buczko, Włodzimierz; Malinski, Tadeusz

    2002-10-01

    This study investigated the process of nitric oxide (NO) release from platelets after stimulation with different angiotensin II type 1 (AT1)-receptor antagonists and its effect on platelet adhesion and aggregation. Angiotensin II AT1-receptor antagonist-stimulated NO release in platelets was compared with that in human umbilical vein endothelial cells by using a highly sensitive porphyrinic microsensor. In vitro and ex vivo effects of angiotensin II AT1-receptor antagonists on platelet adhesion to collagen and thromboxane A2 analog U46619-induced aggregation were evaluated. Losartan, EXP3174, and valsartan alone caused NO release from platelets and endothelial cells in a dose-dependent manner in the range of 0.01 to 100 micro mol/L, which was attenuated by NO synthase inhibitor N(G)-nitro-L-arginine methyl ester. The angiotensin II AT1-receptor antagonists had more than 70% greater potency in NO release in platelets than in endothelial cells. The degree of inhibition of platelet adhesion (collagen-stimulated) and aggregation (U46619-stimulated) elicited by losartan, EXP3174, and valsartan, either in vitro or ex vivo, closely correlated with the NO levels produced by each of these drugs alone. The inhibiting effects of angiotensin II AT1-receptor antagonists on collagen-stimulated adhesion and U46619-stimulated aggregation of platelets were significantly reduced by pretreatment with N(G)-nitro-L-arginine methyl ester. Neither the AT2 receptor antagonist PD123319, the cyclooxygenase synthase inhibitor indomethacin, nor the selective thromboxane A2/prostaglandin H2 receptor antagonist SQ29,548 had any effect on angiotensin II AT1-receptor antagonist-stimulated NO release in platelets and endothelial cells. The presented studies clearly indicate a crucial role of NO in the arterial antithrombotic effects of angiotensin II AT1-receptor antagonists.

  2. [Platelets "Toll-like receptor" engagement stimulates the release of immunomodulating molecules].

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    Cognasse, F; Hamzeh-Cognasse, H; Garraud, O

    2008-09-01

    Platelets are nonnucleated cellular elements that play a role in the process of haemostasis, and also in various ways in innate immunity and in inflammation. Platelets also contain numerous secretory products and can exert critical roles in several aspects of haemostasis. In addition, they house and secrete a variety of cytokines, chemokines and associated molecules which behave as ligands for receptors/counterparts displayed by endothelial cells lining tissue vessels and most leukocyte subsets. These latter studies show that platelets have an important role in innate as well as adaptive immunity; thus platelets can take part in an immune directive response. Moreover, platelets display receptors for several types of cytokines/chemokines along with FcgammaRII receptors. Finally, platelets not only express a variety of Toll-like receptors, with recently identified functions or not as-yet fully identified, but have also been demonstrated to express the key tandem pair of inflammatory and antigen presentation molecules (CD40 and CD40-ligand/CD154), this latter function making them the major purveyors of soluble CD40L in the plasma. It appears that platelets may be regarded as one of the neglected components of immune cell regulators, and platelets contribute to some interesting aspects in bridging innate and adaptive immunity. We propose that platelets discriminate danger signals and adapt the subsequent responses, with polarized cytokine secretion. Platelets may recognize several types of infectious pathogens and limit microbial colonization by sequestering these pathogens and releasing immunomodulatory factors. This review allows us to re-explore indications that platelets exert direct anti-infection immunity and we will present experimentally-driven arguments in favour of a role of platelet TLR in regulating certain immune activities.

  3. Platelets

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    ... tiny fraction of the blood volume. The principal function of platelets is to prevent bleeding. Red blood cells are ... forming a long string. This illustrates the basic function of platelets, to stick to any foreign surface and then ...

  4. Mildly oxidized HDL decrease agonist-induced platelet aggregation and release of pro-coagulant platelet extracellular vesicles.

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    Tafelmeier, M; Fischer, A; Orsó, E; Konovalova, T; Böttcher, A; Liebisch, G; Matysik, S; Schmitz, G

    2017-05-01

    Stored platelet concentrates (PLCs) for therapeutic purpose, develop a platelet storage lesion (PSL), characterized by impaired platelet (PLT) viability and function, platelet extracellular vesicle (PL-EV) release and profound lipidomic changes. Whereas oxidized low-density lipoprotein (oxLDL) activates PLTs and promotes atherosclerosis, effects linked to oxidized high-density lipoprotein (oxHDL) are poorly characterized. PLCs from blood donors were treated with native (nHDL) or mildly oxidized HDL (moxHDL) for 5days under blood banking conditions. Flow cytometry, nanoparticle tracking analysis (NTA), aggregometry, immunoblot analysis and mass spectrometry were carried out to analyze PL-EV and platelet exosomes (PL-EX) release, PLT aggregation, protein expression, and PLT and plasma lipid composition. In comparison to total nHDL, moxHDL significantly decreased PL-EV release by -36% after 5days of PLT storage and partially reversed agonist-induced PLT aggregation. PL-EV release positively correlated with PLT aggregation. MoxHDL improved PLT membrane lipid homeostasis through enhanced uptake of lysophospholipids and their remodeling to corresponding phospholipid species. This also appeared for sphingomyelin (SM) and d18:0/d18:1 sphingosine-1-phosphate (S1P) at the expense of ceramide (Cer) and hexosylceramide (HexCer) leading to reduced Cer/S1P ratio as PLT-viability indicator. This membrane remodeling was associated with increased content of CD36 and maturation of scavenger receptor-B1 (SR-B1) protein in secreted PL-EVs. MoxHDL, more potently than nHDL, improves PLT-membrane lipid homeostasis, partially antagonizes PL-EV release and agonist-induced PLT aggregation. Altogether, this may be the result of more efficient phospho- and sphingolipid remodeling mediated by CD36 and SR-B1 in the absence of ABCA1 on PLTs. As in vitro supplement in PLCs, moxHDL has the potential to improve PLC quality and to prolong storage. Copyright © 2016 Elsevier Ltd. All rights reserved.

  5. Release of ( sup 14 C)5-hydroxytryptamine from human platelets by red wine

    Energy Technology Data Exchange (ETDEWEB)

    Jarman, J.; Glover, V.; Sandler, M. (Queen Charlotte' s and Chelsea Hospital, London (England))

    1991-01-01

    Red wine, at a final dilution of 1/50, caused released of ({sup 14}C)5-hydroxytryptamine (5-HT) from preloaded platelets, an effect which was not observed with any white wines or beers tested. Since 5-HT, is probably released from body stores during migraine attacks and red wine is known to provoke migraine episodes in susceptible individuals, release of 5-HT, possibly from central stores, could represent a plausible mechanism for its mode of action.

  6. Antimicrobial/anti-biofilm activity of expired blood platelets and their released products 

    Directory of Open Access Journals (Sweden)

    Marcin I. Różalski

    2013-04-01

    Full Text Available Introduction. Although platelets are not part of the classical immune system, they have many features that indicate their role in the anti-infective host defense. They come into interactions with microorganisms, which results in co-aggregation and co-adhesion or destruction of themicrobes due to the action of antimicrobial peptides released from platelets.The aim of this study was to evaluate the killing effect of platelets against planktonic and biofilm cultures of Staphylococcus aureus and to test their synergy with antibiotics. Materials and Methods. S. aureus ATCC 29213; platelet rich plasma (1-3 days post shelf life. Evaluation of bactericidal activity of platelets or their lysates against planktonic cultures of S. aureus – CFU calculation after 4- and 24-hour co-incubation. Assessment of S. aureus biofilm viability under the influence of platelets – Live/Dead® BacLightTM Bacterial Viability Kit. Determination of minimum inhibitory concentrations (MICs (oxacillin, vancomycin, linezolid and estimation of the synergistic action of antibiotics and platelet lysates – a gradient-diffusion test strip. Results. Microbicidal activity of “expired” platelets and their lysates has been shown as a significant reduction in the population of staphylococci in their planktonic cultures by 56-87�0and a decrease in metabolic activity of biofilm formation by 7-38�20These activities were enhanced after activation with ADP. Platelet lysates showed a synergistic effect with β-lactam antibiotic (oxacillin and glycopeptide (vancomycin but not with oxazolidinone (linezolid. Conclusions and Discussion. In summary, platelets even after the medical expiry date are still a good source of antimicrobial low molecular weight proteins (PMPs. Testing of bacterialresistance to PMPs may be advisable as a predictive indicator of susceptibility to treatment of infections such as infective endocarditis and other local infections of biofilm nature.

  7. Blood platelet-derived microparticles release and bubble formation after an open-sea air dive.

    Science.gov (United States)

    Pontier, Jean-Michel; Gempp, Emmanuel; Ignatescu, Mihaela

    2012-10-01

    Bubble-induced platelet aggregation offers an index for evaluating decompression severity in humans and in a rat model of decompression sickness. Endothelial cells, blood platelets, or leukocytes shed microparticles (MP) upon activation and during cell apoptosis. The aim was to study blood platelet MP (PMP) release and bubble formation after a scuba-air dive in field conditions. Healthy, experienced divers were assigned to 1 experimental group (n = 10) with an open-sea air dive to 30 msw for 30 min and 1 control group (n = 5) during head-out water immersion for the same period. Bubble grades were monitored with a pulsed doppler according to Kissman Integrated Severity Score (KISS). Blood samples for platelet count (PC) and PMP (annexin V and CD41) were taken 1 h before and after exposure in both groups. The result showed a decrease in post-dive PC compared with pre-dive values in experimental group with no significant change in the control group. We observed a significant increase in PMP values after the dive while no change was revealed in the control group. There was a significant positive correlation between the PMP values after the dive and the KISS bubble score. The present study highlighted a relationship between the post-dive decrease in PC, platelet MP release, and bubble formation. Release of platelet MPs could reflect bubble-induced platelet aggregation and could play a key role in alteration of the coagulation. Further studies must investigate endothelial and leukocyte MP release in the same field conditions.

  8. Effects of the breed, sex and age on cellular content and growth factor release from equine pure-platelet rich plasma and pure-platelet rich gel

    OpenAIRE

    Giraldo Carlos E; López Catalina; Álvarez María E; Samudio Ismael J; Prades Marta; Carmona Jorge U

    2013-01-01

    Abstract Background There is no information on the effects of the breed, gender and age on the cellular content and growth factor (GF) release from equine pure-platelet rich plasma (P-PRP) and pure-platelet rich gel (P-PRG). The objectives of this study were: 1) to compare the cellular composition of P-PRP with whole blood and platelet poor plasma (PPP); 2) to compare the concentration of transforming GF beta 1 (TGF-β1) and platelet derived GF isoform BB (PDGF-BB) between P-PRP treated with n...

  9. Early intraplatelet signaling enhances the release of human platelet PAR-1 and -4 amino-terminal peptides in response to thrombin.

    Science.gov (United States)

    Ofosu, Frederick A; Dewar, Lori; Song, Yingqi; Cedrone, Aisha C; Hortelano, Gonzalo; Craven, Sharon J

    2009-02-24

    Activation of washed human platelets initiated with alpha-thrombin, SFLLRN, or AYPGKF invariably results in the generation of PAR-1-(1-41) and PAR-4-(1-47). PAR-1-(1-41) and PAR-4-(1-47) are amino-terminal peptides generated when PAR-1 and -4 are cleaved in their first extracellular domains after R(41) and R(47), respectively, to expose the tethered ligand domains of PAR-1 and -4. Since soybean trypsin inhibitor decreases generation of PAR-1-(1-41) and PAR-4-(1-47) and other platelet aggregation-related responses to these three agonists, but does not inactivate alpha-thrombin, a platelet trypsin-like proteinase apparently activates PAR-1 and -4 to propagate PAR-dependent platelet responses. This study identified the signaling pathways implicated in the generation of the platelet proteinase that in turn produces PAR-1-(1-41) and PAR-4-(1-47), to thereby drive the subsequent PAR-dependent platelet aggregation-related responses to alpha-thrombin, SFLLRN, or AYPGKF. Only inhibitors of signaling enzymes that prevented ATP release (forskolin, PGE(1), or BIMI-1) prevented or delayed the generation of PAR-1-(1-41) and PAR-4-(1-47) in response to all three agonists. SBTI prevented platelet aggregation initiated by alpha-thrombin, SFLLRN, or AYPGKF but did so less effectively when it was added 10 s after each agonist. Thus, the platelet-derived proteinase acts within 10 s of each agonist addition to generate PAR-1-(1-41) and PAR-4-(1-47). Furthermore, alpha-thrombin may not effectively catalyze PAR-1-(1-41) and PAR-4-(1-47) generation. We propose that unidentified ATP-dependent phosphorylation reactions catalyzed by PKC help to generate the platelet-derived proteinase that propagates human platelet PAR-1 and -4 activation by the three agonists.

  10. Proteomics strategy for identifying candidate bioactive proteins in complex mixtures: application to the platelet releasate.

    LENUS (Irish Health Repository)

    O'Connor, Roisin

    2010-01-01

    Proteomic approaches have proven powerful at identifying large numbers of proteins, but there are fewer reports of functional characterization of proteins in biological tissues. Here, we describe an experimental approach that fractionates proteins released from human platelets, linking bioassay activity to identity. We used consecutive orthogonal separation platforms to ensure sensitive detection: (a) ion-exchange of intact proteins, (b) SDS-PAGE separation of ion-exchange fractions and (c) HPLC separation of tryptic digests coupled to electrospray tandem mass spectrometry. Migration of THP-1 monocytes in response to complete or fractionated platelet releasate was assessed and located to just one of the forty-nine ion-exchange fractions. Over 300 proteins were identified in the releasate, with a wide range of annotated biophysical and biochemical properties, in particular platelet activation, adhesion, and wound healing. The presence of PEDF and involucrin, two proteins not previously reported in platelet releasate, was confirmed by western blotting. Proteins identified within the fraction with monocyte promigratory activity and not in other inactive fractions included vimentin, PEDF, and TIMP-1. We conclude that this analytical platform is effective for the characterization of complex bioactive samples.

  11. Effects of ethanol on aggregation, serotonin release, and amyloid precursor protein processing in rat and human platelets.

    Science.gov (United States)

    Ehrlich, Daniela; Humpel, Christian

    2014-01-01

    It is known that oxidative stress leads to amyloid precursor protein (APP) dysregulation in platelets. Ethanol (EtOH) is a vascular risk factor and induces oxidative stress. The aim of the present study was thus to investigate whether EtOH affects APP processing in rat and human platelets. Platelets were exposed to 50 mM EtOH with and without 2 mM calcium-chloride (CaCl₂) for 20 or 180 minutes at 37°C. Platelet aggregation, serotonin release and APP isoforms 130 and 106/110 kDa were analyzed. As a control, 100 mM H₂O₂ was tested in rat platelets. Our data show that EtOH alone did not affect any of the analyzed parameters, whereas CaCl₂ significantly increased aggregation of rat and human platelets. In addition, CaCl₂ alone enhanced serotonin release in rat platelets. EtOH counteracted CaCl₂-induced aggregation and serotonin release. In the presence of CaCl₂, EtOH reduced the 130 kDa APP isoform in rat and human platelets. In conclusion, this study shows that in the presence of CaCl₂, EtOH affects the platelet function and APP processing in rat and human platelets.

  12. Uptake and release of arachidonic acid by platelets and cultured cells

    Energy Technology Data Exchange (ETDEWEB)

    Neufeld, E.J.

    1985-01-01

    The release by thrombin of arachidonic acid, and the accompanying phospholipid metabolism, were studied in human platelets. At 23/sup 0/C, arachidonate release was half-maximal by 10-30 sec after stimulation, and preceded substantial increase in phosphatidic acid (PA) mass. (/sup 3/H)-glycerol-labeled platelets synthesized phospholipids from (/sup 3/H) PA at a rate of 0.08-0.3 nmol/min/10/sup 9/ cells at 37/sup 0/C. This rate of PA turnover was not enhanced by thrombin stimulation. Thus, an increase in PA mass is not a necessary event in the pathway loading to arachidonate release, and the release of several nmol of arachidonate from PI in the first minute after thrombin stimulation could not have arisen via PA as an intermediate. Biological function of arachidonate-specific acyl-CoA synthetase was examined in platelets and in HSDM/sub 1/C/sub 1/ murine fibrosarcoma cells. Washed platelets were found to take up and esterify into cellular phospholipids eicosanoid precursor fatty acids present at concentrations of 5-500 nM. The uptake process was saturable with respect to fatty acid concentration, with apparent K/sub m/ less than or equal to 85 nM. Stearate, oleate and linoleate were taken up less rapidly, and with higher apparent K/sub m/'s (greater than or equal to 170 nM). High affinity uptake was also found in HSDM/sub 1/C/sub 1/ cells. The fatty acid structural requirements of arachidonoyl-CoA synthetase were examined. Among common mammalian fatty acids, only eicosanoid precursors and docosahexaenoate could serve as substrates. These studies strongly suggest that the synthetase is required for normal eicosanoid homeostasis.

  13. Ex vivo expansion of bovine corneal endothelial cells in xeno-free medium supplemented with platelet releasate.

    Science.gov (United States)

    Chou, Ming-Li; Burnouf, Thierry; Wang, Tsung-Jen

    2014-01-01

    Clinical-grade ex vivo expansion of corneal endothelial cells can increase the availability of corneal tissues for transplantation and treatment of corneal blindness. However, these cells have very limited proliferative capacity. Successful propagation has required so far to use very complex growth media supplemented with fetal bovine serum and other xenocomponents. We hypothesized that human platelet releasates rich in multiple growth factors, and in particular neurotrophins, could potentially be a useful supplement for ex vivo expansion of corneal endothelium cells due to their neural crest origin. Platelet releasates were prepared by calcium salt activation of apheresis platelet concentrates, subjected or not to complement inactivation by heat treatment at 56°C for 30 minutes. Platelet releasates were characterized for their content in proteins and were found to contain high amount of growth factors including platelet-derived growth factor-AB (30.56 to 39.08 ng/ml) and brain-derived neurotrophic factor (30.57 to 37.11 ng/ml) neurotrophins. We compared the growth and viability of corneal endothelium cells in DMEM-F12 medium supplemented with different combinations of components, including 2.5%∼10% of the platelet releasates. Corneal endothelium cells expanded in platelet releasates exhibited good adhesion and a typical hexagonal morphology. Their growth and viability were enhanced when using the complement-inactivated platelet releasate at a concentration of 10%. Immunostaining and Western blots showed that CECs maintained the expressions of four important membrane markers: Na-K ATPase α1, zona occludens-1, phospho-connexin 43 and N-cadherin. In conclusion, our study provides the first proof-of-concept that human platelet releasates can be used for ex vivo expansion of corneal endothelium cells. These findings open a new paradigm for ex vivo propagation protocols of corneal endothelium cells in compliance with good tissue culture practices and regulatory

  14. Ex vivo expansion of bovine corneal endothelial cells in xeno-free medium supplemented with platelet releasate.

    Directory of Open Access Journals (Sweden)

    Ming-Li Chou

    Full Text Available Clinical-grade ex vivo expansion of corneal endothelial cells can increase the availability of corneal tissues for transplantation and treatment of corneal blindness. However, these cells have very limited proliferative capacity. Successful propagation has required so far to use very complex growth media supplemented with fetal bovine serum and other xenocomponents. We hypothesized that human platelet releasates rich in multiple growth factors, and in particular neurotrophins, could potentially be a useful supplement for ex vivo expansion of corneal endothelium cells due to their neural crest origin. Platelet releasates were prepared by calcium salt activation of apheresis platelet concentrates, subjected or not to complement inactivation by heat treatment at 56°C for 30 minutes. Platelet releasates were characterized for their content in proteins and were found to contain high amount of growth factors including platelet-derived growth factor-AB (30.56 to 39.08 ng/ml and brain-derived neurotrophic factor (30.57 to 37.11 ng/ml neurotrophins. We compared the growth and viability of corneal endothelium cells in DMEM-F12 medium supplemented with different combinations of components, including 2.5%∼10% of the platelet releasates. Corneal endothelium cells expanded in platelet releasates exhibited good adhesion and a typical hexagonal morphology. Their growth and viability were enhanced when using the complement-inactivated platelet releasate at a concentration of 10%. Immunostaining and Western blots showed that CECs maintained the expressions of four important membrane markers: Na-K ATPase α1, zona occludens-1, phospho-connexin 43 and N-cadherin. In conclusion, our study provides the first proof-of-concept that human platelet releasates can be used for ex vivo expansion of corneal endothelium cells. These findings open a new paradigm for ex vivo propagation protocols of corneal endothelium cells in compliance with good tissue culture practices

  15. Inhibitory Effect of Clopidogrel on Release of Soluble CD40 Ligand by ADP-activated Platelet in Patients With Non-ST-segment elevation Acute Coronary Syndromes

    Institute of Scientific and Technical Information of China (English)

    Wei Wei; Chufan Luo; Zhimin Du

    2008-01-01

    Objectives To investigate the inhibitory effect of clopidogrel on release of soluble CD40 ligand (sCD40L) by ADP-activated platelet in patients with non-ST-segment elevation acute coronary syndromes(NSTEACS).Methods Forty-two patients with NSTEACS were treated with clopidogrel for 6~8 days.In order to obtain platelet rich plasma (PRP) samples,the venous blood was drawn before and after treatment,respectively.The platelets were activated by adenosine diphosphate (ADP),thus releasing sCD4OL,sCD40L levels were determined by enzyme-linked immunosorbent assay (ELISA) at different time of the reaction.Results Plasma sCD40L concentration before treatment was (0.199±0.155 ) ng/mL,and (0.190±0.176) ng/mL after treatment (P>0.05).Before treatment the PRP sCD40L level at 20-minute of platelet activation was (4.34±2.51 )ng/mL,and decreased to (2.79±1.93 ) ng/mL after treatment (P<0.001).The corresponding level at 40-minute of platelet activation was (5.29±3.13 ) ng/mL before treatment and (2.87±1.59 ) ng/mL after treatment(P<0.001 ).Conclusions Short-term clopidogrel administration might inhibit the release of sCD40L by ADP-activated platelet in patients with NSTEACS,suggesting that,in addition to its antiplatelet potency,clopidogrel may still have an anti-inflammatory effect.

  16. Effects of mibefradil on intracellular Ca2+ release in cultured rat cardiac fibroblasts and human platelets.

    Science.gov (United States)

    Eberhard, M; Miyagawa, K; Hermsmeyer, K; Erne, P

    1995-12-01

    The Ca2+ antagonist mibefradil at supratherapeutic concentrations induced a sustained increase of cytosolic Ca2+ in cultured rat cardiac fibroblasts and human platelets which lack sensitivity to K+ depolarization and Ca2+ channel block by verapamil or other Ca2+ antagonists. At concentrations above 10 microM, mibefradil elevated substantially cytosolic [Ca2+] without affecting the peak level of agonist-induced Ca2+ transients. These Ca2+-mobilizing actions of 10 or 100 microM mibefradil stand in contrast to the Ca2+ antagonism and relaxation of vascular muscle at 1 microM concentrations. Since a substantial part of mibefradil-induced increase in cytosolic Ca2+ was independent of extracellular Ca2+, and in order to define better the mechanism of Ca2+ increase, we exposed permeabilized cultured rat cardiac fibroblasts and human platelets to mibefradil at concentrations sufficiently high to identify covert effects. In permeabilized fibroblasts or platelets mibefradil at concentrations above 10 microM activated dose-dependent Ca2+ release from intracellular Ca2+ stores. Verapamil had no effect at concentrations of up to 100 microM. Mibefradil-induced Ca2+ release was not affected by ryanodine, thapsigargin, removal of ATP or dithioerythreitol, indicating that neither Ca2+ - nor disulfide reagent-induced Ca2+ release were involved and that mibefradil did not release Ca2+ by inhibition of the Ca2+-ATPase pump of endoplasmic reticulum. The rate, but not the amplitude, of mibefradil-induced Ca2+ release is increased up to fourfold in the presence of pentosan polysulphate or heparin, two potent inhibitors of inositol 1,4,5-trisphosphate-induced Ca2+ release. Depletion of Ca2+ stores of permeabilized cells inositol 1,4,5-trisphosphate in the presence of thapsigargin completely blocked mibefradil-induced Ca2+ release, and depletion of Ca2+ stores by mibefradil prevented further Ca2+ release by inositol 1,4,5-trisphosphate. Mibefradil at supratherapeutic concentrations (> or

  17. More on false thrombocytopenias: EDTA-dependent pseudothrombocytopenia associated with a congenital platelet release defect.

    Science.gov (United States)

    Silvestri, F; Masotti, A; Pradella, P; Zaja, F; Barillari, G; De Marco, L

    1996-01-01

    We report herein the case of a 54-year-old woman with a moderate bleeding tendency, diagnosed as an EDTA-dependent pseudothrombocytopenia associated with a congenital platelet release defect. The patient, at the age of 12, had a misleading diagnosis of idiopathic thrombocytopenic purpura and all the recurrent bleeding problems she had during her life were referred to that disease. The recent correct diagnosis of a false thrombocytopenia stimulated further laboratory investigation on the cause of the patient's bleeding tendency with the consequent identification of a congenital platelet deficiency of the arachidonic acid pathway. This finding is of relevant importance for the management of the patient in case of elective surgery or hemorrhagic emergency.

  18. High-density lipoprotein 3 and apolipoprotein A-I alleviate platelet storage lesion and release of platelet extracellular vesicles.

    Science.gov (United States)

    Pienimaeki-Roemer, Annika; Fischer, Astrid; Tafelmeier, Maria; Orsó, Evelyn; Konovalova, Tatiana; Böttcher, Alfred; Liebisch, Gerhard; Reidel, Armin; Schmitz, Gerd

    2014-09-01

    Stored platelet (PLT) concentrates (PLCs) for transfusion develop a PLT storage lesion (PSL), decreasing PLT viability and function with profound lipidomic changes and PLT extracellular vesicle (PL-EV) release. High-density lipoprotein 3 (HDL3 ) improves PLT homeostasis through silencing effects on PLT activation in vivo. This prompted us to investigate HDL3 and apolipoprotein A-I (apoA-I) as PSL-antagonizing agents. Healthy donor PLCs were split into low-volume standard PLC storage bags and incubated with native (n)HDL3 or apoA-I from plasma ethanol fractionation (precipitate IV) for 5 days under standard blood banking conditions. Flow cytometry, Born aggregometry, and lipid mass spectrometry were carried out to analyze PL-EV release, PLT aggregation, agonist-induced PLT surface marker expression, and PLT and plasma lipid compositions. Compared to control, added nHDL3 and apoA-I significantly reduced PL-EV release by up to -62% during 5 days, correlating with the added apoA-I concentration. At the lipid level, nHDL3 and apoA-I antagonized PLT lipid loss (+12%) and decreased cholesteryl ester (CE)/free cholesterol (FC) ratios (-69%), whereas in plasma polyunsaturated/saturated CE ratios increased (+3%) and CE 16:0/20:4 ratios decreased (-5%). Administration of nHDL3 increased PLT bis(monoacylglycero)phosphate/phosphatidylglycerol (+102%) and phosphatidic acid/lysophosphatidic acid (+255%) ratios and improved thrombin receptor-activating peptide 6-induced PLT aggregation (+5%). nHDL3 and apoA-I improve PLT membrane homeostasis and intracellular lipid processing and increase CE efflux, antagonizing PSL-related reduction in PLT viability and function and PL-EV release. We suggest uptake and catabolism of nHDL3 into the PLT open canalicular system. As supplement in PLCs, nHDL3 or apoA-I from Fraction IV of plasma ethanol fractionation have the potential to improve PLC quality to prolong storage. © 2014 AABB.

  19. [Platelet transfusion and allergic transfusion reactions: experiences at Lille Hospital over a four year period].

    Science.gov (United States)

    Wibaut, B; Vannier, V; Renom, P; Goudemand, J

    2000-04-01

    Among the immediate transfusion reactions caused by the utilization of blood products, those suggesting immuno-allergic mechanisms posed problems for frequency, gravity, laboratory diagnosis and safety. We report here the Lille Hospital's experience over a four-year period concerning these manifestations after platelet concentrate transfusion. Eight hundred and fifty-two immediate transfusion reactions have been declared, of which 230 were allergic, which appeared in 181 patients (27%). Among the most frequent clinical signs, rash was often described (158 cases: 68.7%); less frequent were respiratory problems such as dyspnea (34 cases: 14.8%) and hypotensive reactions (18 cases: 7.8%). Seven patients presented severe reactions (3%). Twenty percent of them presented multiple allergic reactions and in 43.2%, the recurrence was more serious than the initial problem in spite of preventive medication; the use of washed blood components was necessary. The age of platelet concentrates does not appear to play a part in provoking these events (67% of platelet concentrates had been collected within four days). These allergic transfusion reactions posed problems for those who prescribe medication, because they are frequent, sometimes serious, can recur and at present, the proposed medication prevention is not always efficient.

  20. Effects of antiplatelet therapy on platelet extracellular vesicle release and procoagulant activity in health and in cardiovascular disease.

    Science.gov (United States)

    Connor, David E; Ly, Ken; Aslam, Anoosha; Boland, John; Low, Joyce; Jarvis, Susan; Muller, David W; Joseph, Joanne E

    2016-12-01

    Dual antiplatelet therapy with aspirin and clopidogrel is commonly used to prevent recurrent ischemic events in patients with cardiovascular disease. Whilst their effects on platelet reactivity are well documented, it is unclear, however, whether antiplatelet therapy inhibits platelet extracellular vesicle (EV) release. The aim of this study was to investigate the effects of antiplatelet therapy on platelet EV formation and procoagulant activity. Blood samples from 10 healthy controls not receiving antiplatelet therapy were incubated in vitro with aspirin or a P2Y12 inhibitor (MeSAMP). Blood samples from 50 patients receiving long-term dual antiplatelet therapy and undergoing coronary angiography were also studied. Platelet reactivity was assessed by Multiplate™ impedance aggregometry. Platelet EV formation and procoagulant activity of pretreated and untreated blood samples in response to arachidonic acid (AA), adenosine diphosphate (ADP), ADP+PGE1, and thrombin receptor-activating peptide (TRAP) stimulation were assessed by flow cytometry and Procoag-PL assays, respectively. Incubation of normal platelets with aspirin significantly inhibited AA-induced platelet reactivity, EV formation, and procoagulant activity, whilst MeSAMP significantly inhibited platelet reactivity and EV formation in response to AA, ADP, and TRAP, but had minimal effect on procoagulant activity. Most patients receiving dual antiplatelet therapy showed an appropriate reduction in platelet reactivity in response to their treatment; however there was not complete inhibition of increased platelet and EV procoagulant activity in response to ADP, AA, or TRAP. In addition, we could not find any correlation between platelet reactivity and procoagulant activity in patients receiving dual antiplatelet therapy.

  1. Recurrent life-threatening reactions to platelet transfusion in an aplastic anaemia patient with a paroxysmal nocturnal haemoglobinuria clone.

    Science.gov (United States)

    Mohamed, M; Bates, G; Richardson, D; Burrows, L

    2014-09-01

    A 60-year-old woman was diagnosed with non-severe aplastic anaemia when she presented with anaemia and thrombocytopenia. She developed recurrent life-threatening hypotensive reactions during transfusion of leukodepleted platelet concentrates, and washed platelet concentrates prevented the development of such reactions subsequently. A paroxysmal nocturnal haemoglobinuria clone was detected on investigating for aplastic anaemia, which has been speculated to play a role in the recurrent hypotensive reactions.

  2. The effect of oxLDL on microvesicle release from platelets, measured by a sensitive flow cytometry method.

    Directory of Open Access Journals (Sweden)

    Tine Bo Nielsen

    2015-11-01

    Full Text Available Microvesicles (MVs are submicron vesicles with sizes of 0.1-1.0-µm in diameter, released from various cell types upon activation or apoptosis. Their involvement in a variety of diseases has been intensively investigated. In blood, platelets are potent MV secretors, and oxLDL, a platelet ligand, induce platelet activation and thus potentially MV secretion. This interaction occurs through binding of oxLDL with CD36, located on the platelet membrane. In this study we investigated the effect of in vitro incubation of platelets with oxLDL on MV release. Furthermore, we compared the results obtained when separating MVs larger than 0.5-µm as a measure of results obtained from less sensitive conventional flow cytometers with MVs below the 0.5-µm limit. MV size-distribution was analysed in plasma from 11 healthy volunteers (4 females, 7 males. MVs were identified as < 1-μm and positive for lactadherin binding and cell specific markers. Platelet rich plasma (PRP was incubated without and with oxLDL or LDL (as control to investigate the impact on platelet activation, evident by release of MVs. Size-calibrated fluorescent beads were used to establish the MV gate, and separate small- and large-size vesicles. CD41+ and CD41+CD36+ MVs increased by 6-8 fold in PRP, when left at room temperature, and the presence of cell specific markers increased. Total MV count was unaffected. Incubations with oxLDL did not increase the MV release or affect the distribution of small- and large-size MVs. We found a large inter-individual variation in the fraction of small- and large-size MVs of 73%. In conclusion, we propose that pro-coagulant activity and activation of platelets induced by interaction of platelet CD36 with oxLDL may not involve release of MVs. Furthermore, our results demonstrate great inter-individual variability in size-distribution of platelet derived MVs and thereby stresses the importance for generation of standardized protocols for MV quantification

  3. Human platelet releasates combined with polyglycolic acid scaffold promote chondrocyte differentiation and phenotypic maintenance

    Indian Academy of Sciences (India)

    Giulia Bernardini; Federico Chellini; Bruno Frediani; Adriano Spreafico; Annalisa Santucci

    2015-03-01

    In the present study, we aimed to demonstrate the differentiating properties of platelet-rich plasma releasates (PRPr) on human chondrocytes seeded on a polygtlycolic acid (PGA) 3D scaffold. Gene expression and biochemical analysis were carried out to assess the improved quality of our PGA-based cartilage constructs supplemented with PRPr. We observed that the use of PRPr as cell cultures supplementation to PGA-chondrocyte constructs may promote chondrocyte differentiation, and thus may contribute to maintaining the chondrogenic phenotype longer than conventional supplementation by increasing high levels of important chondrogenic markers (e.g. sox9, aggrecan and type II collagen), without induction of type I collagen. Moreover, our constructs were analysed for the secretion and deposition of important ECM molecules (sGAG, type II collagen, etc.). Our results indicate that PRPr supplementation may synergize with PGA-based scaffolds to stimulate human articular chondrocyte differentiation, maturation and phenotypic maintenance.

  4. Mechanisms in bradykinin stimulated arachidonate release and synthesis of prostaglandin and platelet activating factor

    Directory of Open Access Journals (Sweden)

    D. Ricupero

    1992-01-01

    Full Text Available Regulatory mechanisms in bradykinin (BK activated release of arachidonate (ARA and synthesis of prostaglandin (PG and platelet activating factor (PAF were studied in bovine pulmonary artery endothelial cells (BPAEC. A role for GTP binding protein (G-protein in the binding of BK to the cells was determined. Guanosine 5-O- (thiotriphosphate, (GTPτS, lowered the binding affinity for BK and increased the Kd for the binding from 0.45 to 1.99 nM. The Bmax remained unaltered at 2.25 × 10-11 mole. Exposure of the cells to aluminium fluoride also reduced the affinity for BK. Bradykinin-induced release of ARA proved pertussis toxin (PTX sensitive, with a maximum sensitivity at 10 ug/ml PTX. GTPτS at 100 μM increased the release of arachidonate. The effect of GTPτS and BK was additive at suboptimal doses of BK up to 0.5 nM but never exceeded the levels of maximal BK stimulation at 50 nM. PTX also inhibited the release of ARA induced by the calcium ionophore, A23187. Phorbol 12-myristate 13-acetate or more commonly known as tetradecanoyl phorbol acetate (TPA itself had little effect on release by the intact cells. However, at 100 nM it augmented the BK activated release. This was downregulated by overnight exposure to TPA and correlated with down-regulation of protein kinase C (PKC activity. The down-regulation only affected the augmentation of ARA release by TPA but not the original BK activated release. TPA displayed a similar, but more potent amplification of PAF synthesis in response to both BK or the calcium ionophore A23187. These results taken together point to the participation of G-protein in the binding of BK to BPAEC and its activation of ARA release. Possibly two types of G-protein are involved, one associated with the receptor, the other activated by Ca2+ and perhaps associated with phospholipase A2 (PLA2. Our results further suggest that a separate route of activation, probably also PLA2 related, takes place through a PKC catalysed

  5. The inhibition of oxygen radical release from human neutrophils by resting platelets is reversed by administration of acetylsalicylic acid or clopidogrel.

    Science.gov (United States)

    Reinisch, C M; Dunzendorfer, S; Pechlaner, C; Ricevuti, G; Wiedermann, C J

    2001-05-01

    Resting platelets inhibit oxygen radical release from neutrophils. Antiplatelet therapy may support this function by preventing platelet activation. Whether antiplatelet agents affect the antioxidative action of resting platelets in the absence of platelet activation is unknown. The effect of acetylsalicylic acid or clopidogrel administration on the antioxidative action of resting platelets was therefore studied in ten healthy volunteers. Preparations of resting platelets were obtained from 5 subjects each - before, during and after an eight-day course of daily treatment with 100 mg of acetylsalicylic acid or 75 mg of the thienopyridine clopidogrel. Human peripheral blood neutrophils were pretreated with the platelets at a ratio of (1/5)0 for 45 min; then formyl-Met-Leu-Phe-triggered oxygen radical release was measured fluorometrically. The inhibitory effect of platelets on oxygen radical release from neutrophils which was seen before treatment was abolished by antiplatelet therapy with either of the drugs, and inhibition was restored gradually after discontinuing acetlsalicylic acid/ clopidogrel intake. Results suggest that the protective role of resting platelets in controlling oxygen radical release from neutrophils in the absence of platelet activation may be impaired by antiplatelet therapy.

  6. Thrombin Receptor-Activating Protein (TRAP-Activated Akt Is Involved in the Release of Phosphorylated-HSP27 (HSPB1 from Platelets in DM Patients

    Directory of Open Access Journals (Sweden)

    Haruhiko Tokuda

    2016-05-01

    Full Text Available It is generally known that heat shock protein 27 (HSP27 is phosphorylated through p38 mitogen-activated protein (MAP kinase. We have previously reported that HSP27 is released from human platelets associated with collagen-induced phosphorylation. In the present study, we conducted an investigation into the effect of thrombin receptor-activating protein (TRAP on the release of HSP27 in platelets in type 2 diabetes mellitus (DM patients. The phosphorylated-HSP27 levels induced by TRAP were directly proportional to the aggregation of platelets. The levels of phosphorylated-HSP27 (Ser-78 were correlated with the levels of phosphorylated-p38 MAP kinase and phosphorylated-Akt in the platelets stimulated by 10 µM TRAP but not with those of phosphorylated-p44/p42 MAP kinase. The levels of HSP27 released from the TRAP (10 µM-stimulated platelets were correlated with the levels of phosphorylated-HSP27 in the platelets. The released platelet-derived growth factor-AB (PDGF-AB levels were in parallel with the HSP27 levels released from the platelets stimulated by 10 µM TRAP. Although the area under the curve (AUC of small aggregates (9–25 µm induced by 10 µM TRAP showed no significant correlation with the released HSP27 levels, AUC of medium aggregates (25–50 µm, large aggregates (50–70 µm and light transmittance were significantly correlated with the released HSP27 levels. TRAP-induced phosphorylation of HSP27 was truly suppressed by deguelin, an inhibitor of Akt, in the platelets from a healthy subject. These results strongly suggest that TRAP-induced activation of Akt in addition to p38 MAP kinase positively regulates the release of phosphorylated-HSP27 from human platelets, which is closely related to the platelet hyper-aggregation in type 2 DM patients.

  7. Effects of the breed, sex and age on cellular content and growth factor release from equine pure-platelet rich plasma and pure-platelet rich gel

    Directory of Open Access Journals (Sweden)

    Giraldo Carlos E

    2013-02-01

    Full Text Available Abstract Background There is no information on the effects of the breed, gender and age on the cellular content and growth factor (GF release from equine pure-platelet rich plasma (P-PRP and pure-platelet rich gel (P-PRG. The objectives of this study were: 1 to compare the cellular composition of P-PRP with whole blood and platelet poor plasma (PPP; 2 to compare the concentration of transforming GF beta 1 (TGF-β1 and platelet derived GF isoform BB (PDGF-BB between P-PRP treated with non-ionic detergent (P-PRP+NID, P-PRG (activated with calcium gluconate -CG-, PPP+NID, PPP gel (PPG, and plasma and; 3 to evaluate and to correlate the effect of the breed, gender and age on the cellular and GF concentration for each blood component. Forty adult horses, 20 Argentinean Creole Horses (ACH and, 20 Colombian Creole Horses (CCH were included. Data were analyzed by parametric (i.e.: t-test, one way ANOVA and non parametric (Kruskal-Wallis test, Wilcoxon test tests. Correlation analysis was also performed by using the Spearman and Pearson tests. A p ≤ 0.05 was set as significant for all tests. All the blood components were compared for platelet (PLT, leukocyte (WBC, TGF-β1 and PDGF-BB concentrations. The effect of the breed, gender and age on these variables was analyzed. A P ≤ 0.05 was accepted as significant for all the tests. Results PLT counts were 1.8 and 0.6 times higher in P-PRP than in whole blood and PPP, respectively; WBC counts were 0.5 and 0.1 times lower in P-PRP, in comparison with whole blood and PPP, respectively. TGF-β1 and PDGF-BB concentrations were 2.3 and 262 times higher, respectively, in P-PRG than in plasma, and 0.59 and 0.48 times higher, respectively, in P-PRG than in PPG. P-PRG derived from CCH females or young horses presented significantly (P Conclusions Our results indicated that P-PRP obtained by a manual method was affected by intrinsic factors such as the breed, gender and age. Equine practitioners should be

  8. A novel collagen/platelet-rich plasma (COL/PRP) scaffold: preparation and growth factor release analysis.

    Science.gov (United States)

    Zhang, Xiujie; Wang, Jingwei; Ren, Mingguang; Li, Lifeng; Wang, Qingwen; Hou, Xiaohua

    2016-06-01

    Platelet-rich plasma (PRP) has been widely used in clinical practice for more than 20 years because it causes the release of many growth factors. However, the burst release pattern and short release period of PRP have become obstacles to its application. An optimal controllable release system is an urgent need for researchers. This study investigated whether collagen/PRP (COL/PRP) scaffolds can serve as a vehicle for the controllable release of growth factors. We fabricated a novel scaffold that integrates PRP activated by thrombin or collagen into type I collagen. The mechanical properties, cytotoxicity, and transforming growth factor β1 (TGF-β1), platelet derived growth factor (PDGF), fibroblast growth factor (FGF) and vascular endothelial growth factor (VEGF) content were evaluated. Our results demonstrate that the COL/PRP scaffolds were not cytotoxic to L-929 fibroblasts. The PDGF and FGF content in the thrombin group was at a higher level and lasted for a long period of time. Collagen and thrombin played the same role in the release of TGF-β1 and VEGF. These data suggest that the novel COL/PRP scaffolds provide a carrier for the controllable release of growth factors and may be used in tissue- regenerative therapies.

  9. Defective PDI release from platelets and endothelial cells impairs thrombus formation in Hermansky-Pudlak syndrome.

    Science.gov (United States)

    Sharda, Anish; Kim, Sarah H; Jasuja, Reema; Gopal, Srila; Flaumenhaft, Robert; Furie, Barbara C; Furie, Bruce

    2015-03-05

    Protein disulfide isomerase (PDI), secreted from platelets and endothelial cells after injury, is required for thrombus formation. The effect of platelet and endothelial cell granule contents on PDI-mediated thrombus formation was studied by intravital microscopy using a mouse model of Hermansky-Pudlak syndrome in which platelet dense granules are absent. Platelet deposition and fibrin generation were nearly absent, and extracellular PDI was significantly reduced in HPS6(-/-) mice after vascular injury. HPS6(-/-) platelets displayed impaired PDI secretion and impaired exocytosis of α granules, lysosomes, and T granules due to decreased sensitivity to thrombin, but these defects could be corrected by addition of subthreshold amounts of adenosine 5'-diphosphate (ADP). Human Hermansky-Pudlak syndrome platelets demonstrated similar characteristics. Infusion of wild-type platelets rescued thrombus formation in HPS6(-/-) mice. Human umbilical vein endothelial cells in which the HPS6 gene was silenced displayed impaired PDI secretion and exocytosis of Weibel-Palade bodies. Defective thrombus formation in Hermansky-Pudlak syndrome, associated with impaired exocytosis of residual granules in endothelial cells and platelets, the latter due to deficiency of ADP, is characterized by a defect in T granule secretion, a deficiency in extracellular PDI secretion, and impaired fibrin generation and platelet aggregation. Hermansky-Pudlak syndrome is an example of a hereditary disease whereby impaired PDI secretion contributes to a bleeding phenotype.

  10. Insulin induces the release of vasodilator compounds from platelets by a nitric oxide-G kinase-VAMP-3-dependent pathway.

    Science.gov (United States)

    Randriamboavonjy, Voahanginirina; Schrader, Jürgen; Busse, Rudi; Fleming, Ingrid

    2004-02-01

    Insulin-induced vasodilatation is sensitive to nitric oxide (NO) synthase (NOS) inhibitors. However, insulin is unable to relax isolated arteries or to activate endothelial NOS in endothelial cells. Since insulin can enhance platelet endothelial NOS activity, we determined whether insulin-induced vasodilatation can be attributed to a NO-dependent, platelet-mediated process. Insulin failed to relax endothelium-intact rings of porcine coronary artery. The supernatant from insulin-stimulated human platelets induced complete relaxation, which was prevented by preincubation of platelets with a NOS inhibitor, the soluble guanylyl cyclase inhibitor, NS 2028, or the G kinase inhibitor, KT 5823, and was abolished by an adenosine A2A receptor antagonist. Insulin induced the release of adenosine trisphosphate (ATP), adenosine, and serotonin from platelet-dense granules in a NO-dependent manner. This response was not detected using insulin-stimulated platelets from endothelial NOS-/- mice, although a NO donor elicited ATP release. Insulin-induced ATP release from human platelets correlated with the association of syntaxin 2 with the vesicle-associated membrane protein 3 but was not associated with the activation of alphaIIbbeta3 integrin. Thus, insulin elicits the release of vasoactive concentrations of ATP and adenosine from human platelets via a NO-G kinase-dependent signaling cascade. The mechanism of dense granule secretion involves the G kinase-dependent association of syntaxin 2 with vesicle-associated membrane protein 3.

  11. Insulin Induces the Release of Vasodilator Compounds From Platelets by a Nitric Oxide–G Kinase–VAMP-3–dependent Pathway

    Science.gov (United States)

    Randriamboavonjy, Voahanginirina; Schrader, Jürgen; Busse, Rudi; Fleming, Ingrid

    2004-01-01

    Insulin-induced vasodilatation is sensitive to nitric oxide (NO) synthase (NOS) inhibitors. However, insulin is unable to relax isolated arteries or to activate endothelial NOS in endothelial cells. Since insulin can enhance platelet endothelial NOS activity, we determined whether insulin-induced vasodilatation can be attributed to a NO-dependent, platelet-mediated process. Insulin failed to relax endothelium-intact rings of porcine coronary artery. The supernatant from insulin-stimulated human platelets induced complete relaxation, which was prevented by preincubation of platelets with a NOS inhibitor, the soluble guanylyl cyclase inhibitor, NS 2028, or the G kinase inhibitor, KT 5823, and was abolished by an adenosine A2A receptor antagonist. Insulin induced the release of adenosine trisphosphate (ATP), adenosine, and serotonin from platelet-dense granules in a NO-dependent manner. This response was not detected using insulin-stimulated platelets from endothelial NOS−/− mice, although a NO donor elicited ATP release. Insulin-induced ATP release from human platelets correlated with the association of syntaxin 2 with the vesicle-associated membrane protein 3 but was not associated with the activation of αIIbβ3 integrin. Thus, insulin elicits the release of vasoactive concentrations of ATP and adenosine from human platelets via a NO–G kinase–dependent signaling cascade. The mechanism of dense granule secretion involves the G kinase–dependent association of syntaxin 2 with vesicle-associated membrane protein 3. PMID:14744991

  12. Bacteria-induced release of white cell--and platelet-derived vascular endothelial growth factor in vitro

    DEFF Research Database (Denmark)

    Nielsen, Hans Jørgen; Werther, K; Mynster, T;

    2001-01-01

    endothelial growth factor (VEGF), may be involved in this process. Therefore, we studied the in vitro release of VEGF from white blood cells and platelets stimulated by bacterial antigens and supernatants from stored red cell components. MATERIALS AND METHODS: Eight units of whole blood (WB) and eight units...... of the supernatants were removed from the units and frozen at -80 degrees C. WB from other healthy donors was stimulated for 2 h with sodium chloride (controls), with Escherichia coli lipopolysaccharide (LPS) alone, or with LPS plus supernatants from the non-filtered or prestorage leucofiltered WB units (diluted 1....... CONCLUSIONS: Extracellular VEGF may accumulate in non-filtered red cell components, but this can be prevented by prestorage leucocyte depletion using filtration. In addition, bacterial antigens appear to induce release of VEGF from white blood cells and platelets. Addition of supernatants from stored, non...

  13. [Experimental research on the effects of different activators on the formation of platelet-rich gel and the release of bioactive substances in human platelet-rich plasma].

    Science.gov (United States)

    Yang, Y; Zhang, W; Cheng, B

    2017-01-20

    Objective: To explore the effects of calcium gluconate and thrombin on the formation of platelet-rich gel (PRG) and the release of bioactive substances in human platelet-rich plasma (PRP) and the clinical significance. Methods: Six healthy blood donors who met the inclusion criteria were recruited in our unit from May to August in 2016. Platelet samples of each donor were collected for preparation of PRP. (1) PRP in the volume of 10 mL was collected from each donor and divided into thrombin activation group (TA, added with 0.5 mL thrombin solution in dose of 100 U/mL) and calcium gluconate activation group (CGA, added with 0.5 mL calcium gluconate solution in dose of 100 g/L) according to the random number table, with 5 mL PRP in each group. Then the PRP of the two groups was activated in water bath at 37 ℃ for 1 h. The formation time of PRG was recorded, and the formation situation of PRG was observed within 1 hour of activation. After being activated for 1 h, one part of PRG was collected to observe the distribution of fibrous protein with HE staining, and another part of PRG was collected to observe platelet ultrastructure under transmission electron microscope (TEM). After being activated for 1 h, the supernatant was collected to determine the content of transforming growth factor β(1, )platelet-derived growth factor BB (PDGF-BB), vascular endothelial growth factor, basic fibroblast growth factor (bFGF), epidermal growth factor, and insulin-like growth factorⅠby enzyme-linked immunosorbent assay. (2) Another 10 mL PRP from each donor was collected and grouped as above, and the platelet suspension was obtained after two times of centrifugation and resuspension with phosphate buffered saline, respectively. And then they were treated with corresponding activator for 1 h as that in experiment (1). Nanoparticle tracking analyzer was used to detect the concentrations of microvesicles with different diameters and total microvesicles derived from platelet. Data

  14. Injectable Biodegradable Polyurethane Scaffolds with Release of Platelet-derived Growth Factor for Tissue Repair and Regeneration

    Science.gov (United States)

    Hafeman, Andrea E.; Li, Bing; Yoshii, Toshitaka; Zienkiewicz, Katarzyna; Davidson, Jeffrey M.; Guelcher, Scott A.

    2013-01-01

    Purpose The purpose of this work was to investigate the effects of triisocyanate composition on the biological and mechanical properties of biodegradable, injectable polyurethane scaffolds for bone and soft tissue engineering. Methods Scaffolds were synthesized using reactive liquid molding techniques, and were characterized in vivo in a rat subcutaneous model. Porosity, dynamic mechanical properties, degradation rate, and release of growth factors were also measured. Results Polyurethane scaffolds were elastomers with tunable damping properties and degradation rates, and they supported cellular infiltration and generation of new tissue. The scaffolds showed a two-stage release profile of platelet-derived growth factor, characterized by a 75% burst release within the first 24 h and slower release thereafter. Conclusions Biodegradable polyurethanes synthesized from triisocyanates exhibited tunable and superior mechanical properties compared to materials synthesized from lysine diisocyanates. Due to their injectability, biocompatibility, tunable degradation, and potential for release of growth factors, these materials are potentially promising therapies for tissue engineering. PMID:18516665

  15. Label-free Detection of Protein Released during Platelet Activation by CNT-Enhanced Love Mode SAW Sensors.

    Science.gov (United States)

    Wu, Huiyan; Zu, Hongfei; Wang, Qing-Ming; Zhao, Gangyi; Wang, Jamesu H-C

    2014-09-01

    Platelet-rich plasma (PRP) has been applied in a series of clinical treatments. PRP contains high-concentrated platelets, which, when activated, could secret a variety of growth factors and cytokines, to promote and/or enhance healing of injured tissues. Non-activated platelets suspension could be prepared by an isolation method of centrifugation and washing currently. However, it is not clear whether platelets, if any, are already activated during this process and there is no simple method to monitor their activation accordingly. Shear-Horizontal Surface Acoustic Wave sensors (SH-SAW, Love Mode) are promising in fundamental biology as well as biomedical engineering, detecting cell behaviors in liquid in a non-invasive, simple and quantitative manner. In this study, Love mode sensors are adopted for the label-free detection of protein secreted by platelets. Carbon nanotube (CNT) is reported as an advisable platform of both non-specific protein adsorption and specific protein binding. For further improvement of Love mode sensor performance, novel CNT -coated parylene-C film is prepared on its surface as both the acoustic-wave-guiding layer and bio-interface layer. The S21 loss curves of Love mode sensors were recorded and the corresponding resonance frequencies were extracted. The results showed that the CNT-enhanced sensor possessed an increased resonance frequency shift when compared to normal sensor with single parylene-C film under identical collagen concentrations. Then, the modified sensor is used for label-free detection of protein released by various concentrations of platelets. The results revealed high sensitivity and consistency, indicating the potential of CNT-enhanced Love mode sensors in cell-based applications.

  16. Effect of ascorbate on plasminogen activator inhibitor-1 expression and release from platelets and endothelial cells in an in-vitro model of sepsis.

    Science.gov (United States)

    Swarbreck, Scott B; Secor, Dan; Ellis, Christopher G; Sharpe, Michael D; Wilson, John X; Tyml, Karel

    2015-06-01

    The microcirculation during sepsis fails due to capillary plugging involving microthrombosis. We demonstrated that intravenous injection of ascorbate reduces this plugging, but the mechanism of this beneficial effect remains unclear. We hypothesize that ascorbate inhibits the release of the antifibrinolytic plasminogen activator inhibitor-1 (PAI-1) from endothelial cells and platelets during sepsis. Microvascular endothelial cells and platelets were isolated from mice. Cells were cultured and stimulated with lipopolysaccharide (LPS), tumor necrosis factor alpha (TNFα), or thrombin (agents of sepsis), with/without ascorbate for 1-24 h. PAI-1 mRNA was determined by quantitative PCR. PAI-1 protein release into the culture medium was measured by ELISA. In platelets, PAI-1 release was measured after LPS, TNFα, or thrombin stimulation, with/without ascorbate. In endothelial cells, LPS and TNFα increased PAI-1 mRNA after 6-24 h, but no increase in PAI-1 release was observed; ascorbate did not affect these responses. In platelets, thrombin, but not LPS or TNFα, increased PAI-1 release; ascorbate inhibited this increase at low extracellular pH. In unstimulated endothelial cells and platelets, PAI-1 is released into the extracellular space. Thrombin increases this release from platelets; ascorbate inhibits it pH-dependently. The data suggest that ascorbate promotes fibrinolysis in the microvasculature under acidotic conditions in sepsis.

  17. Release kinetics of platelet-derived and plasma-derived growth factors from autologous plasma rich in growth factors.

    Science.gov (United States)

    Anitua, Eduardo; Zalduendo, Mari Mar; Alkhraisat, Mohammad Hamdan; Orive, Gorka

    2013-10-01

    Many studies have evaluated the biological effects of platelet rich plasma reporting the final outcomes on cell and tissues. However, few studies have dealt with the kinetics of growth factor delivery by plasma rich in growth factors. Venous blood was obtained from three healthy volunteers and processed with PRGF-Endoret technology to prepare autologous plasma rich in growth factors. The gel-like fibrin scaffolds were then incubated in triplicate, in a cell culture medium to monitor the release of PDGF-AB, VEGF, HGF and IGF-I during 8 days of incubation. A leukocyte-platelet rich plasma was prepared employing the same technology and the concentrations of growth factors and interleukin-1β were determined after 24h of incubation. After each period, the medium was collected, fibrin clot was destroyed and the supernatants were stored at -80°C until analysis. The growth factor delivery is diffusion controlled with a rapid initial release by 30% of the bioactive content after 1h of incubation and a steady state release when almost 70% of the growth factor content has been delivered. Autologous fibrin matrix retained almost 30% of the amount of the growth factors after 8 days of incubation. The addition of leukocytes to the formula of platelet rich plasma did not increase the concentration of the growth factors, while it drastically increased the presence of pro-inflammatory IL-1β. Further studies employing an in vitro inflammatory model would be interesting to study the difference in growth factors and pro-inflammatory cytokines between leukocyte-free and leukocyte-rich platelet rich plasma.

  18. Differential synthesis and release of IL-18 and IL-18 Binding Protein from human platelets and their implications for HIV infection.

    Science.gov (United States)

    Allam, Ossama; Samarani, Suzanne; Jenabian, Mohammad-Ali; Routy, Jean-Pierre; Tremblay, Cecile; Amre, Devendra; Ahmad, Ali

    2017-02-01

    IL-18 is a pro-inflammatory cytokine belonging to the IL-1 family and is produced in the body from macrophages, epithelial and dendritic cells, keratinocytes, adrenal cortex etc. The cytokine is produced as an inactive precursor that is cleaved inside cells into its mature form by activated caspase 1, which exists as an inactive precursor in human cells and requires assembly of an inflammasomes for its activation. We show here for the first time that human platelets contain transcripts for the IL-18 gene. They synthesize the cytokine de novo, process and release it upon activation. The activation also results in the assembly of an inflammasome and activation of caspase-1. Platelets also contain the IL-18 antagonist, the IL-18-Binding Protein (IL-18BP); however, it is not synthesized in them de novo, is present in pre-made form and is released irrespective of platelet activation. IL-18 and IL-18BP co-localize to α granules inside platelets and are secreted out with different kinetics. Platelet activation contributes to plasma concentrations in healthy individuals, as their plasma samples contain abundant IL-18, while their platelet-poor plasma samples contain very little amounts of the cytokine. The plasma and PPP samples from these donors, however, contain comparable amounts of IL-18BP. Unlike healthy individuals, the platelet-poor plasma from HIV-infected individuals contains significant amounts of IL-18. Our findings have important implications for viral infections and other human diseases that are accompanied by platelet activation.

  19. The Role of Platelets in Cardiovascular Disease: Molecular Mechanisms.

    Science.gov (United States)

    Papapanagiotou, Angeliki; Daskalakis, Georgios; Siasos, Gerasimos; Gargalionis, Antonios; Papavassiliou, Athanasios G

    2016-01-01

    The role of platelets in atherosclerotic process and subsequently in the pathophysiology of cardiovascular disease is essential as platelets in addition to their contribution to thrombosis and hemostasis modulating inflammatory reactions and immune response. Platelets after adhesion on the injured vascular endothelium and activation release a wide range of molecules stored in platelets granules such as chemokines, proinflammatory molecules and other biological response modulators accelerating interaction among platelets, endothelial cells and leukocytes. These interactions establish a localized inflammatory response that promotes the atherosclerotic process. Moreover, activated platelets give rise to microparticles another active participant within the blood stream. The purpose of this review is to present the role of platelets in the above mechanisms giving an emphasis on the nature of the platelet derived- molecules and their contribution to the atherosclerotic process.

  20. Platelet-released supernatant induces osteoblastic differentiation of human mesenchymal stem cells: potential role of BMP-2

    Directory of Open Access Journals (Sweden)

    M Alini

    2010-12-01

    Full Text Available Platelet-rich preparations have recently gained popularity in maxillofacial and dental surgery, but their beneficial effect is still under debate. Furthermore, very little is known about the effect of platelet preparations at the cellular level, and the underlying mechanisms. In this study, we tested the effect of platelet-released supernatant (PRS on human mesenchymal stem cell (MSC differentiation towards an osteoblastic phenotype in vitro. Cultures of MSC were supplemented with PRS and typical osteoblastic markers were assessed at up to 28 days post-confluence. PRS showed an osteoinductive effect on MSC, as shown by an increased expression of typical osteoblastic marker genes such as collagen Ialpha1, bone sialoprotein II, BMP-2 and MMP-13, as well as by increased 45Ca2+ incorporation. Our results suggest that the effect of PRS on human MSC could be at least partially mediated by BMP-2.Activated autologous PRS could therefore provide an alternative to agents like recombinant bone growth factors by increasing osteoblastic differentiation of bone precursor cells at bone repair sites, although further studies are needed to fully support our observations.

  1. IgE- and IgG mediated severe anaphylactic platelet transfusion reaction in a known case of cerebral malaria

    Directory of Open Access Journals (Sweden)

    B Shanthi

    2013-01-01

    Full Text Available Background: Allergic reactions occur commonly in transfusion practice. However, severe anaphylactic reactions are rare; anti-IgA (IgA: Immunoglobulin A in IgA-deficient patients is one of the well-illustrated and reported causes for such reactions. However, IgE-mediated hypersensitivity reaction through blood component transfusion may be caused in parasitic hyperimmunization for IgG and IgE antibodies. Case Report: We have evaluated here a severe anaphylactic transfusion reaction retrospectively in an 18year-old male, a known case of cerebral malaria, developed after platelet transfusions. The examination and investigations revealed classical signs and symptoms of anaphylaxis along with a significant rise in the serum IgE antibody level and IgG by hemagglutination method. Initial mild allergic reaction was followed by severe anaphylactic reaction after the second transfusion of platelets. Conclusion: Based on these results, screening of patients and donors with mild allergic reactions to IgE antibodies may help in understanding the pathogenesis as well as in planning for preventive desensitization and measures for safe transfusion.

  2. Effects of drugs on platelet function.

    Science.gov (United States)

    Morse, E E

    1977-01-01

    Numerous drugs and chemicals affect the function of human blood platelets. The mechanism of action of some medications is partly understood. Aspirin is the most frequently involved drug. It appears to interfere with the platelet release reaction by acetylation of a platelet membrane protein which may be involved in the synthesis of prostaglandins. Other anti-inflammatory drugs, including indomethacin, phenylbutazone, ibuprophen (Motrin) and clonixin, also interfere with the release reaction but have a shorter acting course than aspirin. Some drugs stimulate adenylcyclase (gliclazide) or block phosphodiesterase, (dipyridamole, caffeine) both of which actions lead to an increase in adenosine cyclic 3':5' monophosphate (cAMP) and decrease aggregation by adenosine diphosphate (ADP). These interactions should be known to clinical scientists since patients using these medicaments may manifest abnormal platelet function tests in the laboratory and mild hemorrhagic syndromes in the clinic.

  3. Platelet function tests: a comparative review

    Directory of Open Access Journals (Sweden)

    Paniccia R

    2015-02-01

    Full Text Available Rita Paniccia,1,2 Raffaella Priora,1,2 Agatina Alessandrello Liotta,2 Rosanna Abbate1,2 1Department of Experimental and Clinical Medicine, Thrombosis Center, University of Florence, Florence, Italy; 2Department of Heart and Vessels, Azienda Ospedaliero-Universitaria Careggi, Florence, Italy Abstract: 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

  4. Platelet Function Tests in Bleeding Disorders.

    Science.gov (United States)

    Lassila, Riitta

    2016-04-01

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

  5. A Case of Anaphylactic Reaction Following Matsutake Mushroom Ingestion: Demonstration of Histamine Release Reaction of Basophils

    OpenAIRE

    Takako Toda; Masao Yamaguchi; Yuko Nakase; Naoya Sugimoto; Maho Suzukawa; Hiroyuki Nagase; Ken Ohta

    2010-01-01

    Background: Matsutake mushroom is not recognized as a common food allergen. However, several case reports have suggested that this mushroom can induce anaphylaxis on rare occasions. Case Summary: We report a woman with bronchial asthma, who experienced two episodes of Matsutake-induced anaphylaxis. Both the prick-to-prick test and basophil histamine release test showed positive reactions to this mushroom in this patient, but not in control subjects. Discussion: Matsutake mushroom can, o...

  6. Effects of ticlopidine or ticlopidine plus aspirin on platelet aggregation and ATP release in normal volunteers: why aspirin improves ticlopidine antiplatelet activity.

    Science.gov (United States)

    Altman, R; Scazziota, A; Rouvier, J; Gonzalez, C

    1999-10-01

    Aspirin and ticlopidine are used to prevent arterial thrombosis. In some clinical settings ticlopidine is administered with aspirin for improving antithrombotic effect. We administered aspirin (100 mg/day), ticlopidine (500 mg/day), or ticlopidine and aspirin for 7 days to healthy volunteers. Platelet aggregation and ATP release induced by sodium arachidonate, ADP, or a combination of both were measured. Sodium arachidonate (0.25 mmol/L), which produces no platelet aggregation, combined with adenosine diphosphate (1 mumol/L), which produced a reversible platelet aggregation of 20% after ticlopidine, resulted in a synergistic platelet aggregation response in normal (74.6 +/- 9.2%) and in ticlopidine platelet-rich plasma (59.1% +/- 14.9%, p < 0.0001). Synergism after sodium arachidonate (0.75 mmol/L) plus adenosine diphosphate (4 mumol/L) fell from 75.8% +/- 11.0% and 59.1% +/- 15.6% after ticlopidine or aspirin, respectively, to 14.8% +/- 18.0% (p < 0.0001) after ticlopidine plus aspirin. Aspirin and ticlopidine alone did not inhibit adenosine triphosphate release as thoroughly as did aspirin plus ticlopidine. Aspirin or ticlopidine does not adequately prevent platelet activity as ticlopidine plus aspirin do. Addition of aspirin to treatment with ticlopidine improves their antiplatelet activity and better results could be obtained in arterial thrombotic prevention strategies.

  7. [Induction of native platelets aggregation by incubation media of the UV irradiated leukocytes: possible role of the photo-induced ADP release].

    Science.gov (United States)

    Anosov, A K; Gorbach, M M

    2014-01-01

    It is shown that during incubation after UV irradiation (22-24 hours at 7-9 degrees C) irradiated isolated rabbit leukocytes release the compound(s) which induces platelets aggregation in the native platelet rich plasma. Treatment of the incubation media of irradiated leukocytes by heat (5 minutes at 100 degrees C) does not significantly change its pro-aggregation activity. Treatment of the platelet-rich plasma by the incubation media of irradiated leukocytes without stirring induces the refractoriness of platelets to ADP. The platelets treated by ADP without stirring do not react to the incubation media of irradiated leukocytes. The absorption spectrum of the incubation media of irradiated leukocytes has the maximum at 260 nm similar to that of the absorption spectra of ADP. It is possible that UVradiation induces the ADP release from leukocytes during post-irradiation incubation. Accumulation of this substance in the incubation media may be the cause of its pro-aggregation activity for native blood platelets.

  8. Reaction-Multi Diffusion Model for Nutrient Release and Autocatalytic Degradation of PLA-Coated Controlled-Release Fertilizer

    Directory of Open Access Journals (Sweden)

    Sayed Ameenuddin Irfan

    2017-03-01

    Full Text Available A mathematical model for the reaction-diffusion equation is developed to describe the nutrient release profiles and degradation of poly(lactic acid (PLA-coated controlled-release fertilizer. A multi-diffusion model that consists of coupled partial differential equations is used to study the diffusion and chemical reaction (autocatalytic degradation simultaneously. The model is solved using an analytical-numerical method. Firstly, the model equation is transformed using the Laplace transformation as the Laplace transform cannot be inverted analytically. Numerical inversion of the Laplace transform is used by employing the Zakian method. The solution is useful in predicting the nutrient release profiles at various diffusivity, concentration of extraction medium, and reaction rates. It also helps in explaining the transformation of autocatalytic concentration in the coating material for various reaction rates, times of reaction, and reaction-multi diffusion. The solution is also applicable to the other biodegradable polymer-coated controlled-release fertilizers.

  9. Stored platelets alter glycerophospholipid and sphingolipid species, which are differentially transferred to newly released extracellular vesicles.

    Science.gov (United States)

    Pienimaeki-Roemer, Annika; Ruebsaamen, Katharina; Boettcher, Alfred; Orsó, Evelyn; Scherer, Max; Liebisch, Gerhard; Kilalic, Dzenan; Ahrens, Norbert; Schmitz, Gerd

    2013-03-01

    Stored platelet concentrates (PLCs) for transfusion develop a platelet storage lesion (PSL), resulting in decreased platelet (PLT) viability and function. The processes leading to PSL have not been described in detail and no data describe molecular changes occurring in all three components of stored PLCs: PLTs, PLC extracellular vesicles (PLC-EVs), and plasma. Fifty PLCs from healthy individuals were stored under standard blood banking conditions for 5 days. Changes in cholesterol, glycerophospholipid, and sphingolipid species were analyzed in PLTs, PLC-EVs, and plasma by mass spectrometry and metabolic labeling. Immunoblots were performed to compare PLT and PLC-EV protein expression. During 5 days, PLTs transferred glycerophospholipids, cholesterol, and sphingolipids to newly formed PLC-EVs, which increased corresponding lipids by 30%. Stored PLTs significantly increased ceramide (Cer; +53%) and decreased sphingosine-1-phosphate (-53%), shifting sphingolipid metabolism toward Cer. In contrast, plasma accumulated minor sphingolipids. Compared to PLTs, fresh PLC-EVs were enriched in lysophosphatidic acid (60-fold) and during storage showed significant increases in cholesterol, sphingomyelin, dihydrosphingomyelin, plasmalogen, and lysophosphatidylcholine species, as well as accumulation of apolipoproteins A-I, E, and J/clusterin. This is the first detailed analysis of lipid species in all PLC components during PLC storage, which might reflect mechanisms active during in vivo PLT senescence. Stored PLTs reduce minor sphingolipids and shift sphingolipid metabolism toward Cer, whereas in the plasma fraction minor sphingolipids increase. The composition of PLC-EVs resembles that of lipid rafts and confirms their role as carriers of bioactive molecules and master regulators in vascular disease. © 2012 American Association of Blood Banks.

  10. Human Platelet Antigen Alleles in 998 Taiwanese Blood Donors Determined by Sequence-Specific Primer Polymerase Chain Reaction

    Directory of Open Access Journals (Sweden)

    Shun-Chung Pai

    2013-01-01

    Full Text Available Polymorphism of human platelet antigens (HPAs leads to alloimmunizations and immune-mediated platelet disorders including fetal-neonatal alloimmune thrombocytopenia (FNAIT, posttransfusion purpura (PTP, and platelet transfusion refractoriness (PTR. HPA typing and knowledge of antigen frequency in a population are important in particular for the provision of HPA-matched blood components for patients with PTR. We have performed allele genotyping for HPA-1 through -6 and -15 among 998 platelet donors from 6 blood centers in Taiwan using sequence-specific primer polymerase chain reaction. The HPA allele frequency was 99.55, and 0.45% for HPA-1a and -1b; 96.49, and 3.51% for HPA-2a and -2b; 55.81, and 44.19% for HPA-3a and -3b; 99.75, and 0.25% for HPA-4a and -4b; 98.50, and 1.50% for HPA-5a and -5b; 97.75 and 2.25% for HPA-6a and -6b; 53.71 and 46.29% for HPA-15a and -15b. HPA-15b and HPA-3a, may be considered the most important, followed by HPA-2, -6, -1, -5, and -4 systems, as a cause of FNAIT, PTP, and PTR based on allele frequency. HPA-4b and HPA-5b role cannot be excluded based on their immunogenicity. A larger-scale study will now be conducted to confirm these hypotheses and to establish an apheresis donor database for the procurement of HPA-matched apheresis platelets for patients with PTR.

  11. Abciximab treatment in vitro after aspirin treatment in vivo has additive effects on platelet aggregation, ATP release, and P-selectin expression.

    Science.gov (United States)

    Scazziota, A; Altman, R; Rouvier, J; Gonzalez, C; Ahmed, Z; Jeske, W P; Walenga, J M; Fareed, J

    2000-12-15

    To prevent arterial thrombosis, abciximab is administered together with aspirin. However, whether or not there are benefits to combine abciximab with aspirin is not yet well defined. Healthy volunteers were studied for the effect of aspirin + abciximab using sodium arachidonate and adenosine diphosphate (ADP) alone or in combination to induce platelet activation/aggregation. Abciximab produced complete inhibition of platelet aggregation induced with ADP but only 40% inhibition of aggregation induced by 0.75-mmol/l sodium arachidonate. Abciximab added in vitro to platelet-rich plasma (PRP) from platelets from aspirin-treated donors produced an almost complete inhibition of platelet aggregation. Aspirin, and abciximab alone, did not inhibit adenosine triphosphate (ATP) release as thoroughly as aspirin + abciximab did. Abciximab (3-5 microg/ml) produced inhibition of P-selectin expression induced with 5 (from 46.2 +/- 6.0% to 27.4 +/- 7.0%, P=0.002) and 20-micromol/l ADP (from 53.1 +/- 8.1% to 35.1 +/- 11.0%, P=0.019), but no effect was observed when 0.75-mmol/l sodium arachidonate was used (P=0.721). Aspirin diminished P-selectin expression in sodium arachidonate-stimulated platelets (from 77.7 +/- 11.8% to 40.2 +/- 3.6%, P<0.0001) in non-aspirinated and platelets from aspirin-treated donors, respectively. Abciximab (3, 4, and 5 microg/ml) added to platelets from aspirin-treated donors decreased P-selectin expression in platelets stimulated with sodium arachidonate from 40.2 +/- 8.6% to 25.6 +/- 11.5% (P=0.027), to 20.5 +/- 3.5% (P<0.0001), and to 22.5 +/- 1.8% (P<0.0001). We concluded that the antiplatelet effect of abciximab is greatly increased by aspirin.

  12. The protective effect of platelet released growth factors and bone augmentation (Bio-Oss(®)) on ethanol impaired osteoblasts.

    Science.gov (United States)

    Sönmez, Tolga Taha; Bayer, Andreas; Cremer, Tillman; Hock, Jennifer Vanessa Phi; Lethaus, Bernd; Kweider, Nisreen; Wruck, Christoph Jan; Drescher, Wolf; Jahr, Holger; Lippross, Sebastian; Pufe, Thomas; Tohidnezhad, Mersedeh

    2017-07-31

    Chronic alcohol consumption is a known limiting factor for bone healing. One promising strategy to improve bone augmentation techniques with Bio-Oss(®) in oral and maxillofacial surgery might be the supportive application of platelet-concentrated biomaterials as platelet-released growth factor (PRGF). To address this matter, we performed an in vitro study investigating the protective effects of PRGF and Bio-Oss(®) in ethanol (EtOH) treated osteoblasts. The SAOS-2 osteosarcoma cell line, with and without EtOH pretreatment was used. The cell viability, proliferation and alkali phosphatase activity (ALP) after application of 0%, 5% and 10% PRGF and Bio-Oss(®) were assessed. The application of PRGF and Bio-Oss(®) in EtOH impaired osteoblasts showed a significant beneficial influence increasing the viability of the osteoblasts in cell culture. The synergistic effect of Bio-Oss(®) and 5% PRGF on the proliferation of osteoblasts was also demonstrated. Bio-Oss(®) only in combination with PRGF increases the alkaline phosphatase (ALP) activity in EtOH pretreated cells. These results indicate that the simultaneous application of PRGF and Bio-Oss(®) inhibits EtOH induced bone healing impairment. Furthermore, in the cells, PRGF induced a protective mechanism which might promote bone regeneration. Copyright © 2017 Elsevier GmbH. All rights reserved.

  13. The Antimicrobial Peptide Human Beta-Defensin-3 Is Induced by Platelet-Released Growth Factors in Primary Keratinocytes

    Directory of Open Access Journals (Sweden)

    Andreas Bayer

    2017-01-01

    Full Text Available Platelet-released growth factors (PRGF and its related clinically used formulations (e.g., Vivostat Platelet-Rich Fibrin (PRF® contain a variety of chemokines, cytokines, and growth factors and are therefore used to support healing of chronic, hard-to-heal, or infected wounds. Human beta-defensin-3 (hBD-3 is an antimicrobial peptide inducibly expressed in human keratinocytes especially upon wounding. The potent antimicrobial activity of hBD-3 together with its wound closure-promoting activities suggests that hBD-3 may play a crucial role in wound healing. Therefore, we analyzed the influence of PRGF on hBD-3 expression in human primary keratinocytes in vitro. In addition, we investigated the influence of Vivostat PRF on hBD-3 expression in artificially generated human skin wounds in vivo. PRGF treatment of primary keratinocytes induced a significant, concentration- and time-dependent increase in hBD-3 gene expression which was partially mediated by the epidermal growth factor receptor (EGFR. In line with these cell culture data, in vivo experiments revealed an enhanced hBD-3 expression in experimentally produced human wounds after the treatment with Vivostat PRF. Thus, the induction of hBD-3 may contribute to the beneficial effects of thrombocyte concentrate lysates in the treatment of chronic or infected wounds.

  14. Do the fibrin architecture and leukocyte content influence the growth factor release of platelet concentrates? An evidence-based answer comparing a pure platelet-rich plasma (P-PRP) gel and a leukocyte- and platelet-rich fibrin (L-PRF).

    Science.gov (United States)

    Dohan Ehrenfest, David M; Bielecki, Tomasz; Jimbo, Ryo; Barbé, Giovanni; Del Corso, Marco; Inchingolo, Francesco; Sammartino, Gilberto

    2012-06-01

    Platelet concentrates for surgical use are tools of regenerative medicine designed for the local release of platelet growth factors into a surgical or wounded site, in order to stimulate tissue healing or regeneration. Leukocyte content and fibrin architecture are 2 key characteristics of all platelet concentrates and allow to classify these technologies in 4 families, but very little is known about the impact of these 2 parameters on the intrinsic biology of these products. In this demonstration, we highlight some outstanding differences in the growth factor and matrix protein release between 2 families of platelet concentrate: Pure Platelet-Rich Plasma (P-PRP, here the Anitua's PRGF - Preparation Rich in Growth Factors - technique) and Leukocyte- and Platelet-Rich Fibrin (L-PRF, here the Choukroun's method). These 2 families are the extreme opposites in terms of fibrin architecture and leukocyte content. The slow release of 3 key growth factors (Transforming Growth Factor β1 (TGFβ1), Platelet-Derived Growth Factor AB (PDGF-AB) and Vascular Endothelial Growth Factor (VEGF)) and matrix proteins (fibronectin, vitronectin and thrombospondin-1) from the L-PRF and P-PRP gel membranes in culture medium is described and discussed. During 7 days, the L-PRF membranes slowly release significantly larger amounts of all these molecules than the P-PRP gel membranes, and the 2 products display different release patterns. In both platelet concentrates, vitronectin is the sole molecule to be released almost completely after only 4 hours, suggesting that this molecule is not trapped in the fibrin matrix and not produced by the leukocytes. Moreover the P-PRP gel membranes completely dissolve in the culture medium after less than 5 days only, while the L-PRF membranes are still intact after 7 days. This simple demonstration shows that the polymerization and final architecture of the fibrin matrix considerably influence the strength and the growth factor trapping/release potential

  15. Activated platelets release two types of membrane vesicles: microvesicles by surface shedding and exosomes derived from exocytosis of multivesicular bodies and alpha-granules.

    Science.gov (United States)

    Heijnen, H F; Schiel, A E; Fijnheer, R; Geuze, H J; Sixma, J J

    1999-12-01

    Platelet activation leads to secretion of granule contents and to the formation of microvesicles by shedding of membranes from the cell surface. Recently, we have described small internal vesicles in multivesicular bodies (MVBs) and alpha-granules, and suggested that these vesicles are secreted during platelet activation, analogous to the secretion of vesicles termed exosomes by other cell types. In the present study we report that two different types of membrane vesicles are released after stimulation of platelets with thrombin receptor agonist peptide SFLLRN (TRAP) or alpha-thrombin: microvesicles of 100 nm to 1 microm, and exosomes measuring 40 to 100 nm in diameter, similar in size as the internal vesicles in MVBs and alpha-granules. Microvesicles could be detected by flow cytometry but not the exosomes, probably because of the small size of the latter. Western blot analysis showed that isolated exosomes were selectively enriched in the tetraspan protein CD63. Whole-mount immuno-electron microscopy (IEM) confirmed this observation. Membrane proteins such as the integrin chains alpha(IIb)-beta(3) and beta(1), GPIbalpha, and P-selectin were predominantly present on the microvesicles. IEM of platelet aggregates showed CD63(+) internal vesicles in fusion profiles of MVBs, and in the extracellular space between platelet extensions. Annexin-V binding was mainly restricted to the microvesicles and to a low extent to exosomes. Binding of factor X and prothrombin was observed to the microvesicles but not to exosomes. These observations and the selective presence of CD63 suggest that released platelet exosomes may have an extracellular function other than the procoagulant activity, attributed to platelet microvesicles.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1988-06-01

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

  17. Release of transforming growth factor beta 1 and platelet derived growth factor type AB from canine platelet gels obtained by the tube method and activated with calcium salts

    OpenAIRE

    RF Silva; GC Santana; FOP Leme; JU Carmona; CMF Rezende

    2013-01-01

    The objectives of this study were: 1) to measure the concentrations of transforming growth factor beta 1 (TGF-β1) and platelet-derived growth factor type AB (PDGF-AB) in plasma and platelet gel (PG) activated with calcium salts (gluconate or chloride) in dogs, and 2) to determine correlations between cell results and growth factors (GF) concentrations. Blood samples were collected from fourteen Brazilian Fila dogs. EDTA was used to obtain whole blood and plasma while ACD-A solution was used t...

  18. Role of pH Changes on Transforming Growth Factor-β1 Release and on the Fibrin Architecture of Platelet-rich Fibrin When Layered with Biodentine, Glass Ionomer Cement, and Intermediate Restorative Material.

    Science.gov (United States)

    Mullaguri, Harish; Suresh, Nandini; Surendran, Smitha; Velmurugan, Natanasabapathy; Chitra, Selvarajan

    2016-05-01

    The purpose of this study was to evaluate the influence of pH that is due to setting reaction of Biodentine, glass ionomer cement (GIC), and intermediate restorative material (IRM) on transforming growth factor-β1 (TGF-β1) release and on the fibrin architecture of platelet-rich fibrin (PRF). PRF was obtained from 8 volunteers and layered over the freshly prepared GIC, IRM, and Biodentine mixtures. TGF-β1 release was estimated by using enzyme-linked immunosorbent assay (ELISA), and fibrin structure of PRF was analyzed by using scanning electron microscope at 1 and 5 hours. Biodentine, GIC, and IRM increased the TGF-β1 release in comparison with that of control group (PRF alone) at both 1 and 5 hours. Biodentine released significantly more TGF-β1 than GIC and IRM at 1 hour. At 5 hours both GIC and Biodentine released significantly more TGF-β1 than IRM. The fibrin architecture of the Biodentine group was similar to that of control group at both 1 and 5 hours. In GIC and IRM groups the fibrillar structure of fibrin was collapsed, ill-defined, and cloudy with very thick fibers and irregularly reduced porosities. Biodentine induces larger amount of TGF-β1 release and also maintains the integrity of fibrin structure when compared with GIC and IRM when layered over PRF. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  19. In-vitro release pharmacokinetics of amikacin, teicoplanin and polyhexanide in a platelet rich fibrin?layer (PRF)?a laboratory evaluation of a modern, autologous wound treatment

    OpenAIRE

    Knafl, Daniela; Thalhammer, Florian; Vossen, Matthias G.

    2017-01-01

    Objectives Platelet rich fibrin (PRF) is an autologous fibrin glue, produced from patients' blood, which, besides intraoperative use, has applications in the treatment of infected wounds. The combination with antimicrobial agents results in a prolonged antibacterial effect allowing for wound dressing change intervals of seven days even in infected wounds. The aim of this study was to evaluate release kinetics of amikacin, teicoplanin or polyhexanide from a PRF-layer. Methods PRF mixed with te...

  20. Lack of the specific influence of histamine and histamine H1, H2 and H3 receptor ligands on the serotonin uptake and release in rat blood platelets.

    Science.gov (United States)

    Pawlak, D; Malinowska, B; Wollny, T; Godlewski, G; Buczko, W

    1996-01-01

    This work was designed to investigate the influence of histamine, and H1 receptor agonist 2-(2-thiazolyl)ethylamine, H2 receptor agonist dimaprit and H3 receptor agonist R-(-)-alpha-methylhistamine on the serotonin uptake and release in rat blood platelets. Histamine and R-(-)-alpha-methylhistamine (up to 1 mmol/l), 2-(2-thiazolyl)ethylamine (up to 10 mumol/l) and dimaprit (up to 1 mumol/l) failed to affect the serotonin uptake. The concentration-dependent inhibitory effects of higher concentrations of 2-(2-thiazolyl)ethylamine and dimaprit (up to 1 mmol/l) were not diminished by the H1 receptor antagonist dimetindene and the H2 receptor antagonist ranitidine (1 and 100 mumol/l each), respectively. Histamine, 2-(2-thiazolyl)ethylamine, dimaprit and R-(-)-alpha-methylhistamine (up to 10 mumol/l) did not change the serotonin release from rat blood platelets. Our results demonstrate that histamine and histamine H1, H2 and H3 receptor agonists do not affect in a specific manner the serotonin uptake and release in rat blood platelets.

  1. In vitro release of growth factors from platelet-rich fibrin (PRF): a proposal to optimize the clinical applications of PRF.

    Science.gov (United States)

    Su, Chen Yao; Kuo, Ya Po; Tseng, Yu Hong; Su, Ching-Hua; Burnouf, Thierry

    2009-07-01

    Determine the release of growth factors (GF) from platelet-rich fibrin (PRF) and supernatant serum to optimize clinical use. Platelet-derived growth factors-AB (PDGF-AB), transforming growth factor-beta1 (TGF-beta1), vascular endothelial growth factor (VEGF), epidermal growth factor (EGF), and insulin-like growth factor-1 (IGF-1) were quantified in PRF releasate and in the supernatant serum (N = 8) over 300 minutes after clot formation. Protein profiles were determined by SDS-PAGE. Mean quantity of PDGF-AB, TGF-ss1, VEGF, and EGF in PRF releasate increased significantly to about 52, 72, 1, and 3 ng, respectively, whereas mean IGF-1 content remained at 250 ng. GF was also found in serum supernatant. Protein profiles of the releasates and the supernatant serum were similar. The PRF membrane should be used immediately after formation to maximize release of GF to the surgical site. The remaining fluid can be recovered as an additional source of GF for grafting.

  2. Adhering maternal platelets can contribute to the cytokine and chemokine cocktail released by human first trimester villous placenta.

    Science.gov (United States)

    Blaschitz, A; Siwetz, M; Schlenke, P; Gauster, M

    2015-11-01

    Placental villous explant culture has been increasingly recognized as suitable model to study secretion of inflammatory and immune modulating factors by human placenta. Most of these factors likely derive from the syncytiotrophoblast, whereas extraplacental sources such as maternal peripheral blood cells are rarely considered. Due to their small size and absence of a nucleus, platelets adhering to perivillous fibrinoid of normal placenta are frequently ignored in routine immunohistochemistry. Here we demonstrate adhering maternal platelets on first trimester placental villi after explant culture and point out that platelet-derived factors must be considered when analyzing the inflammatory secretion profile of human placenta.

  3. Platelet-Rich Gel Supernatants Stimulate the Release of Anti-Inflammatory Proteins on Culture Media of Normal Equine Synovial Membrane Explants.

    Science.gov (United States)

    Ríos, Diana L; López, Catalina; Carmona, Jorge U

    2015-01-01

    The aims were as follows: (1) to evaluate the effects at 48 and 96 h of two concentrations (25 and 50%) of leukocyte and platelet-rich gel (L-PRG) and pure PRG (P-PRG) supernatants on the production/degradation in normal equine synovial membrane explants (SME) of platelet derived growth factor isoform BB, transforming growth factor beta-1, tumor necrosis factor alpha, interleukin (IL-) 4 (IL-4), IL-1 receptor antagonist (IL-1ra), and hyaluronan (HA) synthesis and (2) to correlate these molecules with their respective PRG supernatant treatments. SME from 6 horses were cultured for 96 h with L-PRG and P-PRG supernatants at 25 and 50% concentrations, respectively. SME culture media were changed each 48 h and used for determination by ELISA of the molecules, which were also determined in synovial fluid. 25% L-PRG supernatant produced a sustained release over time of IL-1ra and a gradual release of HA, whereas 50% L-PRG supernatant produced a sustained increase over time of IL-4 and HA. 50% P-PRG supernatant produced an increased and sustained production of IL-1ra and IL-4. The cellular composition and the articular concentration (volume) of a platelet-rich plasma preparation could affect the anti-inflammatory and anabolic joint responses in horses with osteoarthritis.

  4. Reduction of relative centrifugal forces increases growth factor release within solid platelet-rich-fibrin (PRF)-based matrices: a proof of concept of LSCC (low speed centrifugation concept).

    Science.gov (United States)

    El Bagdadi, K; Kubesch, A; Yu, X; Al-Maawi, S; Orlowska, A; Dias, A; Booms, P; Dohle, E; Sader, R; Kirkpatrick, C J; Choukroun, J; Ghanaati, S

    2017-03-21

    Purpose The present study evaluated the platelet distribution pattern and growth factor release (VEGF, TGF-β1 and EGF) within three PRF (platelet-rich-fibrin) matrices (PRF, A-PRF and A-PRF+) that were prepared using different relative centrifugation forces (RCF) and centrifugation times. Materials and methods immunohistochemistry was conducted to assess the platelet distribution pattern within three PRF matrices. The growth factor release was measured over 10 days using ELISA. Results The VEGF protein content showed the highest release on day 7; A-PRF+ showed a significantly higher rate than A-PRF and PRF. The accumulated release on day 10 was significantly higher in A-PRF+ compared with A-PRF and PRF. TGF-β1 release in A-PRF and A-PRF+ showed significantly higher values on days 7 and 10 compared with PRF. EGF release revealed a maximum at 24 h in all groups. Toward the end of the study, A-PRF+ demonstrated significantly higher EGF release than PRF. The accumulated growth factor releases of TGF-β1 and EGF on day 10 were significantly higher in A-PRF+ and A-PRF than in PRF. Moreover, platelets were located homogenously throughout the matrix in the A-PRF and A-PRF+ groups, whereas platelets in PRF were primarily observed within the lower portion. ​Discussion the present results show an increase growthfactor release by decreased RCF. However, further studies must be conducted to examine the extent to which enhancing the amount and the rate of released growth factors influence wound healing and biomaterial-based tissue regeneration. ​Conclusion These outcomes accentuate the fact that with a reduction of RCF according to the previously LSCC (described low speed centrifugation concept), growth factor release can be increased in leukocytes and platelets within the solid PRF matrices.

  5. Effects of Anti-CD59 on Complement- induced Platelet Activation in Adult Males with Coronary Heart Disease

    Institute of Scientific and Technical Information of China (English)

    王礼春; 马虹; 黄守坚; 麦炜颐; 董吁钢; 曾武涛; 廖新学; 何建桂; 徐冬

    2003-01-01

    Objectives To study the reactions of platelet to active complement and the ef-fects of anti- CD59 on platelet activation induced bycomplement in coronary heart disease (CHD) adultmales. Methods By applying cobra venom factor(CVF) to activate complement, observed the plateletaggregation and release reactions induced by activecomplement with or without applying anti- CD59 toblock the complement modulation protein CD59.Results CVF could induce platelet of CHD individ-uals release ATP and cause significant and lastingmetamorphosis, but failed to induce platelet aggregate.The platelet maximum shape change showed positivelinear correlation with lg concentration of CVF. Theregressive equation was Y=28.7171gx - 19. 798 ( r =0. 956, P <0.01, n = 36). Anti - CD59 could enhanceCVF- induced platelet shape change and ATP releasewith a dose-dependent manner. ConclusionsComplement activated by CVF can induce significantand lasting platelet metamorphosis and release reac-tion, but can't induce platelet aggregation in CHD adultmales. Anti -CD59 can promote the platelet reactionsinduced by active complement.

  6. Efficacy of the controlled release of concentrated platelet lysate from a collagen/gelatin scaffold for dermis-like tissue regeneration.

    OpenAIRE

    Ito, Ran; Morimoto, Naoki; Pham, Liem Hieu; Taira, Tsuguyoshi; Kawai, Katsuya; Suzuki, Shigehiko

    2013-01-01

    Introduction: A collagen/gelatin scaffold (CGS) can provide a sustained release of basic fibroblast growth factor (bFGF), which promotes wound healing. However, bFGF is approved for clinical use in Japan and China only. One potential alternative to bFGF is platelet lysate (PL), a safe and easily attainable source of a wide range of growth factors necessary for tissue repair. In the present study, we investigated the use of PL with CGS to repair wounds and identified the optimal concentration ...

  7. Structure-activity relationship studies of 1-substituted 3-dodecanoylindole-2-carboxylic acids as inhibitors of cytosolic phospholipase A2-mediated arachidonic acid release in intact platelets.

    Science.gov (United States)

    Griessbach, Klaus; Klimt, Monika; Schulze Elfringhoff, Alwine; Lehr, Matthias

    2002-01-01

    A series of 3-dodecanoylindole-2-carboxylic acid derivatives with varied carboxylic acid substituents at the indole 1-position were synthesized and evaluated for their ability to inhibit arachidonic acid release in human platelets mediated by the cytosolic phospholipase A(2). Structure-activity relationship studies revealed that increasing the polarity of these substituents by the introduction of additional polar groups in the proximity of the carboxylic acid moiety reduced activity. Conformational restriction of the indole-1-carboxylic acid substituents in distinct positions as well as extending the length of these residues led to compounds which did not substantially differ in their potencies.

  8. Tetrandrine differentially inhibits aggregation and ATP-release of rat platelets%粉防己碱特异抑制大鼠血小板聚集和ATP释放

    Institute of Scientific and Technical Information of China (English)

    陳一岳; 關超然; 許少珍

    1996-01-01

    To examine the effects of tetrandrine (Tet)on the aggregation and ATP-release of rat washed platelets induced by several platelet activators.METHODS: Gel-filtration (Sepharose 2B) was used to isolate washed platelets from adult rats and the platelet aggragation and ATP-release were measured simultaneously. RESULTS: In the presence of Ca2+ 1 mmol·L-1, Tet 300 μmol·L-1 inhibited the aggregation induced by ADP (25μmol· L- 1 ), collagen (2.5 g·L-1), and thrombin (103 unit·L-1)by 62 %, 60 %, and 34 %, respectively. It also inhibited arachidonic acid ( 1 mmol· L- 1 )-induced aggregation. Elevating intracellular Ca2+ concentration with the Ca2+ ionophore, calcimycin (30μmol· L-1), or by blocking the intracellular calcium pump with cyclopiazonic acid (5 μmol· L-1) initiated platelet aggregation, which was also inhibited by Tet. In Ca2 + -free medium, Tet still elicited an inhibitory effect on aggregation induced by ristocetin(2.5 g· L- 1). Lower concentrations of Tet (30nmol· L-1 to 3 μmol· L-1) failed to inhibit the aggregation (requiring Tet 10 - 300 μmol· L- 1 ), but strongly suppressed ATP-release induced by ADP 10μmol· L- 1, both of which were measured simultaneously in a single sample. CONCLUSION: Tet elicits a nonselective inhibitory effect on platelet aggregation not solely due to its Ca2+ antagonism and may act on a final common pathway leading to platelet aggregation. Furthermore, Tet is a much potent inhibitor of the release of ATP in platelets.

  9. Effects of irradiation on platelet function

    Energy Technology Data Exchange (ETDEWEB)

    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.

  10. Junín virus infection of human hematopoietic progenitors impairs in vitro proplatelet formation and platelet release via a bystander effect involving type I IFN signaling.

    Science.gov (United States)

    Pozner, Roberto G; Ure, Agustín E; Jaquenod de Giusti, Carolina; D'Atri, Lina P; Italiano, Joseph E; Torres, Oscar; Romanowski, Victor; Schattner, Mirta; Gómez, Ricardo M

    2010-04-15

    Argentine hemorrhagic fever (AHF) is an endemo-epidemic disease caused by Junín virus (JUNV), a member of the arenaviridae family. Although a recently introduced live attenuated vaccine has proven to be effective, AHF remains a potentially lethal infection. Like in other viral hemorrhagic fevers (VHF), AHF patients present with fever and hemorrhagic complications. Although the causes of the bleeding are poorly understood, impaired hemostasis, endothelial cell dysfunction and low platelet counts have been described. Thrombocytopenia is a common feature in VHF syndromes, and it is a major sign for its diagnosis. However, the underlying pathogenic mechanism has not yet been elucidated. We hypothesized that thrombocytopenia results from a viral-triggered alteration of the megakaryo/thrombopoiesis process. Therefore, we evaluated the impact of JUNV on megakaryopoiesis using an in vitro model of human CD34+ cells stimulated with thrombopoietin. Our results showed that CD34+ cells are infected with JUNV in a restricted fashion. Infection was transferrin receptor 1 (TfR1)-dependent and the surface expression of TfR1 was higher in infected cultures, suggesting a novel arenaviral dissemination strategy in hematopoietic progenitor cells. Although proliferation, survival, and commitment in JUNV-infected cultures were normal, viral infection impaired thrombopoiesis by decreasing in vitro proplatelet formation, platelet release, and P-selectin externalization via a bystander effect. The decrease in platelet release was also TfR1-dependent, mimicked by poly(I:C), and type I interferon (IFN alpha/beta) was implicated as a key paracrine mediator. Among the relevant molecules studied, only the transcription factor NF-E2 showed a moderate decrease in expression in megakaryocytes from either infected cultures or after type I IFN treatment. Moreover, type I IFN-treated megakaryocytes presented ultrastructural abnormalities resembling the reported thrombocytopenic NF-E2(-/-) mouse

  11. Hydrogen release from Mg(NH2)2-MgH2 through mechanochemical reaction.

    Science.gov (United States)

    Hu, Jianjiang; Wu, Guotao; Liu, Yongfeng; Xiong, Zhitao; Chen, Ping; Murata, Kenji; Sakata, Ko; Wolf, Gerd

    2006-08-03

    A total of 7.4 wt % of hydrogen was released from the mixture of magnesium amide and magnesium hydride at a molar ratio of 1:2 by mechanical ball milling. Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction (XRD) characterizations along with the amount of hydrogen released at different stages of ball milling reveal that magnesium imide was first formed in the reaction. The imide then reacted continuously with magnesium hydride and was converted to magnesium nitride and hydrogen. Thermodynamic calculation shows that the hydrogen desorption is a mild endothermic reaction with the standard enthalpy change of about 3.5 kJ/mol of H2.

  12. A Case of Anaphylactic Reaction Following Matsutake Mushroom Ingestion: Demonstration of Histamine Release Reaction of Basophils

    Directory of Open Access Journals (Sweden)

    Takako Toda

    2010-01-01

    Discussion: Matsutake mushroom can, on rare occasions, cause anaphylaxis in sensitized people, a reaction so far observed only in Japan. Not ony the in vivo prick-to-prick test but also the in vitro basophil activation test utilizing the patient's blood represent useful methods for allergen identification and also for identification of sensitized subjects.

  13. Molecular Basis Linking Platelet to Inflammation

    Institute of Scientific and Technical Information of China (English)

    马丽萍

    2010-01-01

    @@ Introduction Blood platelets not only play an important role in hemostasis and thrombosis,but increasing evidence show that they participate in the induction of inflammation.Firstly,platelets contain and release cytokines and immune mediators.And platelets are able to modulate and regulate the function of surrounding cells by adhesion molecules or by the release of various factors.

  14. Angiogenesis is regulated by a novel mechanism: pro- and antiangiogenic proteins are organized into separate platelet α granules and differentially released

    OpenAIRE

    Italiano, Joseph E.; Richardson, Jennifer L.; Patel-Hett, Sunita; Battinelli, Elisabeth; Zaslavsky, Alexander; Short, Sarah; Ryeom, Sandra; Folkman, Judah; Klement, Giannoula L.

    2008-01-01

    Platelets, in addition to their function in hemostasis, play an important role in wound healing and tumor growth. Because platelets contain angiogenesis stimulators and inhibitors, the mechanisms by which platelets regulate angiogenesis remain unclear. As platelets adhere to activated endothelium, their action can enhance or inhibit local angiogenesis. We therefore suspected a higher organization of angiogenesis regulators in platelets. Using double immunofluorescence and immunoelectron micro...

  15. A radial basis function (RBF) finite difference method for the simulation of reaction-diffusion equations on stationary platelets within the augmented forcing method

    Science.gov (United States)

    Shankar, Varun; Wright, Grady B.; Fogelson, Aaron L.; Kirby, Robert M.

    2014-05-01

    We present a computational method for solving the coupled problem of chemical transport in a fluid (blood) with binding/unbinding of the chemical to/from cellular (platelet) surfaces in contact with the fluid, and with transport of the chemical on the cellular surfaces. The overall framework is the Augmented Forcing Point Method (AFM) (\\emph{L. Yao and A.L. Fogelson, Simulations of chemical transport and reaction in a suspension of cells I: An augmented forcing point method for the stationary case, IJNMF (2012) 69, 1736-52.}) for solving fluid-phase transport in a region outside of a collection of cells suspended in the fluid. We introduce a novel Radial Basis Function-Finite Difference (RBF-FD) method to solve reaction-diffusion equations on the surface of each of a collection of 2D stationary platelets suspended in blood. Parametric RBFs are used to represent the geometry of the platelets and give accurate geometric information needed for the RBF-FD method. Symmetric Hermite-RBF interpolants are used for enforcing the boundary conditions on the fluid-phase chemical concentration, and their use removes a significant limitation of the original AFM. The efficacy of the new methods are shown through a series of numerical experiments; in particular, second order convergence for the coupled problem is demonstrated.

  16. Effect of ionizing radiation on platelet function in vitro

    Energy Technology Data Exchange (ETDEWEB)

    Kalovidouris, A.E.; Papayannis, A.G. (Evangelismos Hospital, Athens (Greece))

    1981-01-01

    The effect of ionizing radiation on platelet function was investigated in vitro. Platelet-rich plasma (300x10/sup 9//l) was irradiated with doses of 1, 4, 10, 20 and 50 Gy. Platelet function tests were performed on both irradiated and control (non-irradiated) platelet samples. The platelet function tests were (1) platelet aggregation by ADP (1, 2, 4 ..mu..mol final concentration), adrenaline and collagen, (2) ADP-release from platelets, (3) clot retraction and (4) platelet factor-3 availability. It was found that roentgen irradiation of platelets in vitro did not affect these platelet function tests.

  17. Platelets as delivery systems for disease treatments

    OpenAIRE

    Shi, Qizhen; Montgomery, Robert R.

    2010-01-01

    Platelets are small, anucleate, discoid shaped blood cells that play a fundamental role in hemostasis. Platelets contain a large number of biologically active molecules within cytoplasmic granules that are critical to normal platelet function. Because platelets circulate in blood through out the body, release biological molecules and mediators on demand, and participate in hemostasis as well as many other pathophysiologic processes, targeting expression of proteins of interest to platelets an...

  18. Carbon dioxide released from subduction zones by fluid-mediated reactions

    Science.gov (United States)

    Ague, Jay J.; Nicolescu, Stefan

    2014-05-01

    The balance between the subduction of carbonate mineral-bearing rocks into Earth's mantle and the return of CO2 to the atmosphere by volcanic and metamorphic degassing is critical to the carbon cycle. Carbon is thought to be released from subducted rocks mostly by simple devolatilization reactions. However, these reactions will also retain large amounts of carbon within the subducting slab and have difficulty in accounting for the mass of CO2 emitted from volcanic arcs. Carbon release may therefore occur via fluid-induced dissolution of calcium carbonate. Here we use carbonate δ18O and δ13C systematics, combined with analyses of rock and fluid inclusion mineralogy and geochemistry, to investigate the alteration of the exhumed Eocene Cycladic subduction complex on the Syros and Tinos islands, Greece. We find that in marble rocks adjacent to two fluid conduits that were active during subduction, the abundance of calcium carbonate drastically decreases approaching the conduits, whereas silicate minerals increase. Up to 60-90% of the CO2 was released from the rocks--far greater than expected via simple devolatilization reactions. The δ18O of the carbonate minerals is 5-10 lighter than is typical for metamorphosed carbonate rocks, implying that isotopically light oxygen was transported by fluid infiltration from the surroundings. We suggest that fluid-mediated carbonate mineral removal, accompanied by silicate mineral precipitation, provides a mechanism for the release of enormous amounts of CO2 from subduction zones.

  19. AD6 (8-monochloro-3-beta-diethylamino-ethyl-4-methyl-7-ethoxycarbonyl-meth oxy coumarin) inhibits the release of arachidonic acid in human platelets stimulated by thrombin

    Energy Technology Data Exchange (ETDEWEB)

    Porcellati, S.; Costantini, V.; Prosdocimi, M.; Pistolesi, R.; Porrovecchio, P.; Nenci, G.G.; Goracci, G.

    1987-07-01

    The coumarin derivative AD6 is known to inhibit platelet aggregation and release and it possesses vasodilatory properties on coronary arteries of laboratory animals. Furthermore, the inhibition of the production of TxB2 from endogenous substrates after stimulation of human platelets with collagen has been demonstrated. The present report demonstrates that AD6 inhibits the production of labeled arachidonic acid and diglycerides from phospholipids of platelets stimulated with thrombin. This effect is dose-dependent and is already evident at a concentration of the drug (25 microM) which is unable to prevent the aggregation. Apparently, AD6 inhibits the release of arachidonic acid from phosphatidylinositol and choline phosphoglycerides which are the main sources of the substrate for the synthesis of prostaglandins and thromboxanes.

  20. Drug effects on platelet adherence to collagen and damaged vessel walls.

    Science.gov (United States)

    Packham, M A; Cazenave, J P; Kinlough-Rathbone, R L; Mustard, J F

    1978-01-01

    The interaction of platelets with damaged vessel walls leads to the formation of platelet-fibrin thrombi and may also contribute to the development of atherosclerotic lesions because platelets adherent to exposed collagen release a mitogen that stimulates smooth muscle cell proliferation. The first step in thrombus formation, platelet adherence to an injured vessel wall, can be studied quantitatively by the use of platelets labeled with 51chromium. In these investigations, rabbit aortas were damaged by passage of a balloon catheter and segments of the aortas were everted on probes that were rotated in platelet suspensions. Collagen-coated glass cylinders were also used. Adherence was measured in a medium containing approximately physiologic concentrations of calcium, magnesium, protein and red blood cells. Conditions of testing influence the effect of non-steroidal anti-inflammatory drugs, sulfinpyrazone, and dipyridamole on platelet adherence. Aspirin and sulfinpyrazone were not inhibitory when tested in a medium with a 40% hematocrit; this indicates that products formed by platelets from arachidonate probably do not play a major part in the adherence of the first layer of platelets to the surface, although they may be involved in thrombus formation. Indomethacin, dipyridamole, prostaglandin E1, methylprednisolone and penicillin G and related antibiotics did inhibit platelet adherence although the concentrations required were higher than would likely be achieved in vivo upon administration to human patients. None of the non-steroidal anti-inflammatory drugs inhibited the release of granule contents from adherent platelets. Pretreatment of the damaged vessel wall with aspirin increased platelet adherence, presumably because it prevented the formation of PGI2 by the vessel wall. Platelet adherence to undamaged or damaged vessel walls was enhanced by prior exposure of the wall to thrombin. Platelet reactions with aggregating agents and platelet survival can be

  1. In-vitro release pharmacokinetics of amikacin, teicoplanin and polyhexanide in a platelet rich fibrin-layer (PRF)-a laboratory evaluation of a modern, autologous wound treatment.

    Science.gov (United States)

    Knafl, Daniela; Thalhammer, Florian; Vossen, Matthias G

    2017-01-01

    Platelet rich fibrin (PRF) is an autologous fibrin glue, produced from patients' blood, which, besides intraoperative use, has applications in the treatment of infected wounds. The combination with antimicrobial agents results in a prolonged antibacterial effect allowing for wound dressing change intervals of seven days even in infected wounds. The aim of this study was to evaluate release kinetics of amikacin, teicoplanin or polyhexanide from a PRF-layer. PRF mixed with teicoplanin, amikacin or polyhexanide was sprayed on a silicon gauze patch and put on a colombia agar with bacteria with known minimal inhibitory concentration (MIC) and incubated for 24 hours and afterwards transferred to another agar with the same bacterial strain. Inhibition zones were measured every 24 hours. This was repeated on 7 consecutive days. Antibiotic concentrations were calculated by interpolation. More than 1000 mg/L teicoplanin were released within the first 24 hours and 28.22 mg/L after 168 hours. Amikacin release was above 10,000 mg/L within the first 24 hours and still 120.8 mg/L after 120 hours. A release of polyhexanide could be verified for the first 24 hours only. Consequently teicoplanin and amikacin released from PRF showed antimicrobial in-vitro effects for almost a week, whereas an antimicrobial effect of polyhexanide could only be verified for the first 24 hours. Our Results show that a weekly dressing regimen may be justified in wounds treated with PRF plus amikacin or teicoplanin, since bacteria will be eradicated over a considerable period of time after a single application of PRF.

  2. The effect of salmeterol and salbutamol on mediator release and skin responses in immediate and late phase allergic cutaneous reactions

    DEFF Research Database (Denmark)

    Petersen, Lars Jelstrup; Skov, P S

    1999-01-01

    by suction blister technique. RESULTS: Both beta2-agonists inhibited allergen-induced histamine release and wheal and flare reactions with maximum inhibition of 40-50% at 10(-6) M, a concentration which reduced PGD2 synthesis by approximately 55%. Histamine release by codeine and skin reactions to codeine...

  3. Platelet-rich fibrin (PRF): a second-generation platelet concentrate. Part II: platelet-related biologic features.

    Science.gov (United States)

    Dohan, David M; Choukroun, Joseph; Diss, Antoine; Dohan, Steve L; Dohan, Anthony J J; Mouhyi, Jaafar; Gogly, Bruno

    2006-03-01

    Platelet-rich fibrin (PRF) belongs to a new generation of platelet concentrates, with simplified processing and without biochemical blood handling. In this second article, we investigate the platelet-associated features of this biomaterial. During PRF processing by centrifugation, platelets are activated and their massive degranulation implies a very significant cytokine release. Concentrated platelet-rich plasma platelet cytokines have already been quantified in many technologic configurations. To carry out a comparative study, we therefore undertook to quantify PDGF-BB, TGFbeta-1, and IGF-I within PPP (platelet-poor plasma) supernatant and PRF clot exudate serum. These initial analyses revealed that slow fibrin polymerization during PRF processing leads to the intrinsic incorporation of platelet cytokines and glycanic chains in the fibrin meshes. This result would imply that PRF, unlike the other platelet concentrates, would be able to progressively release cytokines during fibrin matrix remodeling; such a mechanism might explain the clinically observed healing properties of PRF.

  4. HUMAN PLATELET ANTIGEN-1 (ZW) TYPING OF FETUSES BY ANALYSIS OF POLYMERASE CHAIN REACTION-AMPLIFIED GENOMIC DNA FROM AMNIOCYTES

    NARCIS (Netherlands)

    SIMSEK, S; CHRISTIAENS, GCLM; KANHAI, HHH; BEEKHUIS, [No Value; BLEEKER, PMM; VLEKKE, ABJ; GOLDSCHMEDING, R; VONDEMBORNE, AEGK

    1994-01-01

    Prenatal typing for the human platelet antigens-l (HPA) permits identification of a fetus at risk for neonatal alloimmune thrombocytopenia (NAITP) in cases of HPA-1 incompatibility in which the father is heterozygous for the HPA-la antigen. Diagnostic cordocentesis and phenotyping of the fetal plate

  5. Body-Fitted Detonation Shock Dynamics and the Pseudo-Reaction-Zone Energy Release Model

    Science.gov (United States)

    Meyer, Chad; Quirk, James; Short, Mark; Chqiuete, Carlos

    2016-11-01

    Programmed-burn methods are a class of models used to propagate a detonation wave, without the high resolution cost associated with a direct numerical simulation. They separate the detonation evolution calculation into two components: timing and energy release. The timing component is usually calculated with a Detonation Shock Dynamics model, a surface evolution representation that relates the normal velocity of the surface (Dn) to its local curvature. The energy release component must appropriately capture the degree of energy change associated with chemical reaction while simultaneously remaining synchronized with the timing component. The Pseudo-Reaction-Zone (PRZ) model is a reactive burn like energy release model, converting reactants into products, but with a conversion rate that is a function of the DSD surface Dn field. As such, it requires the DSD calculation produce smooth Dn fields, a challenge in complex geometries. We describe a new body-fitted approach to the Detonation Shock Dynamics calculation which produces the required smooth Dn fields, and a method for calibrating the PRZ model such that the rate of energy release remains as synced as possible with the timing component. We show results for slab, rate-stick and arc geometries.

  6. 烧伤后血小板流变行为及其调节研究进展%Advances in the research of rheological behavior of platelets and its regulation after burn

    Institute of Scientific and Technical Information of China (English)

    张庆富

    2014-01-01

    Microcirculatory dysfunction of local wounds and distant tissues after burns results in ischemia and hypoxia of tissues and organs,thus affecting the course and prognosis of burns.Platelet is an important component of blood,and the changes in its rheological behavior influence the blood flow in the microcirculation,as well as the microvascular structure and function.The abnormality of platelet rheological behavior plays an important role in the occurrence and development of microcirculatory dysfunction after burn.Changes in rheological behavior of platelets are due to changes in platelet morphology,adhesion,aggregation,shrinkage functions,and release reaction.Investigation of platelet rheological behavior and its regulation after burn may be of significant implication in the analysis of patient's condition and instruction for treatment.This article reviews the changes in platelet rheological behavior and its regulation after burn in the aspects of morphology,adhesion,aggregation,shrinkage functions,and release reaction.

  7. 单采血小板献血反应的诱因分析总结%Analysis and summary the inducement of platelets aphaeresis donated reaction

    Institute of Scientific and Technical Information of China (English)

    陈蓓怡

    2014-01-01

    目的:预防和降低单采血小板过程中献血反应的发生,保证单采质量,壮大无偿献血队伍。方法:对天津市2010年-2013年发生献血反应的单采献血者情况进行记录并分析。结果:单采血小板发生献血反应的诱因主要包括:精神紧张,枸橼酸盐反应,低血糖反应,身体因素,二次穿刺。结论:做好献血前的宣传告知工作和献血过程中的护理干预,是保证单采过程顺利进行的重要措施之一。%Objective:To prevent and reduce the occurrence of donated reaction in the process of platelet apheresis,ensure the apheresis quality,and strengthen blood donation team.Methods:The situation of solid blood donors with donated reaction from 2010 to 2013 in Tianjin were recorded and analysed.Results:The inducement of platelets aphaeresis donated reaction mainly include:mental stress,citrate reaction,hypoglycemia reaction,physical factors,and the two puncture.Conclusion:Complete the propaganda inform work before blood donation and nursing intervention in the process of blood donation,is one of the important measures to ensure the single production process smoothly.

  8. Platelets and cardiac arrhythmia

    Directory of Open Access Journals (Sweden)

    Jonas S De Jong

    2010-12-01

    Full Text Available Sudden cardiac death remains one of the most prevalent modes of death in industrialized countries, and myocardial ischemia due to thrombotic coronary occlusion is its primary cause. The role of platelets in the occurrence of SCD extends beyond coronary flow impairment by clot formation. Here we review the substances released by platelets during clot formation and their arrhythmic properties. Platelet products are released from three types of platelet granules: dense core granules, alpha-granules, and platelet lysosomes. The physiologic properties of dense granule products are of special interest as a potential source of arrhythmic substances. They are released readily upon activation and contain high concentrations of serotonin, histamine, purines, pyrimidines, and ions such as calcium and magnesium. Potential arrhythmic mechanisms of these substances, e.g. serotonin and high energy phosphates, include induction of coronary constriction, calcium overloading, and induction of delayed after-depolarizations. Alpha-granules produce thromboxanes and other arachidonic acid products with many potential arrhythmic effects mediated by interference with cardiac sodium, calcium and potassium channels. Alpha-granules also contain hundreds of proteins that could potentially serve as ligands to receptors on cardiomyocytes. Lysosomal products probably do not have an important arrhythmic effect. Platelet products and ischemia can induce coronary permeability, thereby enhancing interaction with surrounding cardiomyocytes. Antiplatelet therapy is known to improve survival after myocardial infarction. Although an important part of this effect results from prevention of coronary clot formation, there is evidence to suggest that antiplatelet therapy also induces anti-arrhythmic effects during ischemia by preventing the release of platelet activation products.

  9. Platelet mimicry

    DEFF Research Database (Denmark)

    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...

  10. Platelet Count

    Science.gov (United States)

    ... their spleen removed surgically Use of birth control pills (oral contraceptives) Some conditions may cause a temporary (transitory) increased ... increased platelet counts include estrogen and birth control pills (oral contraceptives). Mildly decreased platelet counts may be seen in ...

  11. Platelets and infection — an emerging role of platelets in viral infection

    Directory of Open Access Journals (Sweden)

    Alice eAssinger

    2014-12-01

    Full Text Available Platelets are anucleate blood cells that play a crucial role in the maintenance of hemostasis. While platelet activation and elevated platelet counts (thrombocytosis are associated with increased risk of thrombotic complications, low platelet counts (thrombocytopenia and several platelet function disorders increase the risk of bleeding. Over the last years more and more evidence has emerged that platelets and their activation state can also modulate innate and adaptive immune responses and low platelet counts have been identified as a surrogate marker for poor prognosis in septic patients.Viral infections often coincide with platelet activation. Host inflammatory responses result in the release of platelet activating mediators and a pro-oxidative and pro-coagulant environment, which favours platelet activation. However, viruses can also directly interact with platelets and megakaryocytes and modulate their function. Furthermore, platelets can be activated by viral antigen-antibody complexes and in response to some viruses B-lymphocytes also generate anti-platelet antibodies.All these processes contributing to platelet activation result in increased platelet consumption and removal and often lead to thrombocytopenia, which is frequently observed during viral infection. However, virus-induced platelet activation does not only modulate platelet count, but also shapes immune responses. Platelets and their released products have been reported to directly and indirectly suppress infection and to support virus persistence in response to certain viruses, making platelets a double-edged sword during viral infections. This review aims to summarize the current knowledge on platelet interaction with different types of viruses, the viral impact on platelet activation and platelet-mediated modulations of innate and adaptive immune responses.

  12. Platelets and infection - an emerging role of platelets in viral infection.

    Science.gov (United States)

    Assinger, Alice

    2014-01-01

    Platelets are anucleate blood cells that play a crucial role in the maintenance of hemostasis. While platelet activation and elevated platelet counts (thrombocytosis) are associated with increased risk of thrombotic complications, low platelet counts (thrombocytopenia) and several platelet function disorders increase the risk of bleeding. Over the last years, more and more evidence has emerged that platelets and their activation state can also modulate innate and adaptive immune responses and low platelet counts have been identified as a surrogate marker for poor prognosis in septic patients. Viral infections often coincide with platelet activation. Host inflammatory responses result in the release of platelet activating mediators and a pro-oxidative and pro-coagulant environment, which favors platelet activation. However, viruses can also directly interact with platelets and megakaryocytes and modulate their function. Furthermore, platelets can be activated by viral antigen-antibody complexes and in response to some viruses B-lymphocytes also generate anti-platelet antibodies. All these processes contributing to platelet activation result in increased platelet consumption and removal and often lead to thrombocytopenia, which is frequently observed during viral infection. However, virus-induced platelet activation does not only modulate platelet count but also shape immune responses. Platelets and their released products have been reported to directly and indirectly suppress infection and to support virus persistence in response to certain viruses, making platelets a double-edged sword during viral infections. This review aims to summarize the current knowledge on platelet interaction with different types of viruses, the viral impact on platelet activation, and platelet-mediated modulations of innate and adaptive immune responses.

  13. Identification of two major ammonia-releasing reactions involved in secondary natto fermentation.

    Science.gov (United States)

    Kada, Shigeki; Yabusaki, Masahiro; Kaga, Takayuki; Ashida, Hitoshi; Yoshida, Ken-ichi

    2008-07-01

    Natto is a traditional Japanese food made from soybeans fermented by strains of Bacillus subtilis natto. It gives off a strong ammonia smell during secondary fermentation, and the biochemical basis for this ammonia production was investigated in this study. When natto was fermented by strain r22, ammonia production was shown to involve degradation of soybean proteins releasing amino acids, and only the glutamate contained in the natto obviously decreased, while the other amino acids increased during secondary fermentation. Strain r22 has two active glutamate dehydrogenase genes, rocG and gudB, and inactivating both genes reduced ammonia production by half, indicating that deamination of glutamate was one of the major ammonia-releasing reactions. In addition, urease encoded by ureABC was found to degrade urea during secondary fermentation. A triple mutant lacking rocG, gudB, and ureC exhibited minimal ammonia production, suggesting that the degradation of urea might be a further ammonia-releasing reaction.

  14. Assessment of released acrosin activity as a measurement of the sperm acrosome reaction

    Institute of Scientific and Technical Information of China (English)

    Rui-Zhi Liu; Wan-Li Na; Hong-Guo Zhang; Zhi-Yong Lin; Bai-Oong Xue; Zong-Oe Xu

    2008-01-01

    Aim: To develop a method for assessing sperm function by measuring released acrosin activity during the acrosome reaction (AR). Methods: Human semen samples were obtained from 24 healthy donors with proven fertility after 3-7 days of sexual abstinence. After collection, samples were liquefied for 30 min at room temperature. Standard semen parameters were evaluated according to World Health Organization (WHO) criteria. Calcium ionophore A23187 and progesterone (P4) were used to stimulate the sperm to undergo AR. After treatment, sperm were incubated with the supravital dye Hoechst33258, fixed in a glutaraldehyde-phosphate-buffered saline solution, and the acrosomal status was determined by fluorescence microscopy with fluorescein isothiocyanate-labeled Pisum sativum agglutinin (FITC-PSA). The percentage of sperm undergoing AR (AR%) was compared to sperm acrosin activities as assessed by spectrocolorimetry. The correlation between AR% and acrosin activity was determined by statistical analysis. Results: The AR% and released acrosin activity were both markedly increased with A23187 and P4 stimulation. Sperm motility and viability were significantly higher after stimulation with P4 versus stimula-tion with A23187 (P < 0.001). There was a significant positive correlation between released acrosin activity and AR% determined by FITC-PSA staining (r = 0.916, P < 0.001). Conclusion: Spectrocolorimetric measurement of released acrosin activity might serve as a reasonable alternative method to evaluate AR.

  15. Stimulation of Platelet Death by Vancomycin

    Directory of Open Access Journals (Sweden)

    Syeda T. Towhid

    2013-01-01

    Full Text Available Background/Aims: Side effects of vancomycin, a widely used antibiotic, include thrombocytopenia. The vancomycin-induced thrombocytopenia has been attributed to immune reactions. At least in theory, thrombocytopenia could result in part from the triggering of apoptosis, which results in cell shrinkage and cell membrane scrambling with subsequent phosphatidylserine exposure at the cell surface. The cell membrane scrambling could be initiated by a signaling involving increase of cytosolic Ca2+ activity, ceramide formation, mitochondrial depolarization and/or caspase activation. Vancomycin has indeed been shown to trigger neutrophil apoptosis. An effect of vancomycin on platelet apoptosis has, however, never been tested. The present study thus explored the effect of vancomycin on platelet activation and apoptosis. Methods: Human blood platelets were exposed to vancomycin and forward scatter was utilized to estimate cell volume, annexin V-binding to quantify phosphatidylserine (PS exposure, Fluo-3 AM fluorescence to estimate cytosolic Ca2+ activity ([Ca2+]i, antibodies to quantify ceramide formation and immunofluorescence to quantify protein abundance of active caspase-3. Results: A 30 minutes exposure to vancomycin (≥1 µg/ ml decreased cell volume, triggered annexin V-binding, increased [Ca2+]i, activated caspase 3, stimulated ceramide formation, triggered release of thromboxane B2, and upregulated surface expression of CD62P (P-selectin as well as activated integrin αllbβ3. Annexin V-binding and upregulation of CD62P (P-selectin and integrin αllbβ3 was significantly blunted by removal of extracellular Ca2+. Annexin V-binding was not significantly blunted by pan-caspase inhibitor zVAD-FMK (1 µM. In conclusion, vancomycin results in platelet activation and suicidal platelet death with increase of [Ca2+]i, caspase-3 activation, cell membrane scrambling and cell shrinkage. Activation and cell membrane scrambling required the presence of Ca2

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

    OpenAIRE

    Silva Raul F; Carmona Jorge U; Rezende Cleuza MF

    2012-01-01

    Abstract 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) conce...

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

    OpenAIRE

    Silva, Raul F; Carmona, Jorge U; Rezende, Cleuza MF

    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 ...

  18. Platelets, inflammation and tissue regeneration.

    Science.gov (United States)

    Nurden, Alan T

    2011-05-01

    Blood platelets have long been recognised to bring about primary haemostasis with deficiencies in platelet production and function manifesting in bleeding while upregulated function favourises arterial thrombosis. Yet increasing evidence indicates that platelets fulfil a much wider role in health and disease. First, they store and release a wide range of biologically active substances including the panoply of growth factors, chemokines and cytokines released from a-granules. Membrane budding gives rise to microparticles (MPs), another active participant within the blood stream. Platelets are essential for the innate immune response and combat infection (viruses, bacteria, micro-organisms). They help maintain and modulate inflammation and are a major source of pro-inflammatory molecules (e.g. P-selectin, tissue factor, CD40L, metalloproteinases). As well as promoting coagulation, they are active in fibrinolysis; wound healing, angiogenesis and bone formation as well as in maternal tissue and foetal vascular remodelling. Activated platelets and MPs intervene in the propagation of major diseases. They are major players in atherosclerosis and related diseases, pathologies of the central nervous system (Alzheimers disease, multiple sclerosis), cancer and tumour growth. They participate in other tissue-related acquired pathologies such as skin diseases and allergy, rheumatoid arthritis, liver disease; while, paradoxically, autologous platelet-rich plasma and platelet releasate are being used as an aid to promote tissue repair and cellular growth. The above mentioned roles of platelets are now discussed.

  19. Does Platelet-Rich Plasma Freeze-Thawing Influence Growth Factor Release and Their Effects on Chondrocytes and Synoviocytes?

    Directory of Open Access Journals (Sweden)

    Alice Roffi

    2014-01-01

    Full Text Available PRP cryopreservation remains a controversial point. Our purpose was to investigate the effect of freezing/thawing on PRP molecule release, and its effects on the metabolism of chondrocytes and synoviocytes. PRP was prepared from 10 volunteers, and a half volume underwent one freezing/thawing cycle. IL-1β, HGF, PDGF AB/BB, TGF-β1, and VEGF were assayed 1 hour and 7 days after activation. Culture media of chondrocytes and synoviocytes were supplemented with fresh or frozen PRP, and, at 7 days, proliferation, gene expression, and secreted proteins levels were evaluated. Results showed that in the freeze-thawed PRP the immediate and delayed molecule releases were similar or slightly lower than those in fresh PRP. TGF-β1 and PDGF AB/BB concentrations were significantly reduced after freezing both at 1 hour and at 7 days, whereas HGF concentration was significantly lower in frozen PRP at 7 days. In fresh PRP IL-1β and HGF concentrations underwent a significant further increase after 7 days. Similar gene expression was found in chondrocytes cultured with both PRPs, whereas in synoviocytes HGF gene expression was higher in frozen PRP. PRP cryopreservation is a safe procedure, which sufficiently preserves PRP quality and its ability to induce proliferation and the production of ECM components in chondrocytes and synoviocytes.

  20. Effect of Puumala hantavirus infection on Human Umbilical Vein Endothelial Cell hemostatic function: platelet interactions, increased tissue factor expression and fibrinolysis regulator release

    Directory of Open Access Journals (Sweden)

    Marco eGoeijenbier

    2015-03-01

    Full Text Available Puumala virus (PUUV infection causes over 5000 cases of hemorrhagic fever in Europe annually and can influence the hemostatic balance extensively. Infection might lead to hemorrhage, while a recent study showed an increased risk of myocardial infarction during or shortly after PUUV infection. The mechanism by which this hantavirus influences the coagulation system remains unknown. Therefore we aimed to elucidate mechanisms explaining alterations seen in primary and secondary hemostasis during PUUV infection. By using low passage PUUV isolates to infect primary human umbilical vein endothelial cells (HUVECs we were able to show alterations in the regulation of primary- and secondary hemostasis and in the release of fibrinolysis regulators. Our main finding was an activation of secondary hemostasis due to increased tissue factor expression leading to increased thrombin generation in a functional assay. Furthermore, we showed that during infection platelets adhered to HUVECs and subsequently specifically to PUUV virus particles. Infection of HUVECs with PUUV did not result in increased von Willebrand factor while they produced more plasminogen activator inhibitor type-1 (PAI-1 compared to controls. The PAI-1 produced in this model formed complexes with vitronectin. This is the first report that reveals a potential mechanism behind the pro-coagulant changes in PUUV patients, which could be the result of increased thrombin generation due to an increased tissue factor expression on endothelial cells during infection. Furthermore, we provide insight into the contribution of endothelial cell responses regarding hemostasis in PUUV pathogenesis.

  1. Enhancement of osteogenic differentiation of human adipose derived stem cells by the controlled release of platelet lysates from hybrid scaffolds produced by supercritical fluid foaming.

    Science.gov (United States)

    Santo, Vítor E; Duarte, Ana Rita C; Popa, Elena G; Gomes, Manuela E; Mano, João F; Reis, Rui L

    2012-08-20

    A new generation of scaffolds capable of acting not only as support for cells but also as a source of biological cues to promote tissue regeneration is currently a hot topic of in bone Tissue Engineering (TE) research. The inclusion of growth factor (GF) controlled release functionalities in the scaffolds is a possible strategy to achieve such goal. Platelet Lysate (PL) is an autologous source of GFs, providing several bioactive agents known to act on bone regeneration. In this study, chitosan-chondroitin sulfate nanoparticles loaded with PL were included in a poly(D,L-lactic acid) foam produced by supercritical fluid foaming. The tridimensional (3D) structures were then seeded with human adipose-derived stem cells (hASCs) and cultured in vitro under osteogenic stimulus. The osteogenic differentiation of the seeded hASCs was observed earlier for the PL-loaded constructs, as shown by the earlier alkaline phosphatase peak and calcium detection and stronger Runx2 expression at day 7 of culture, in comparison with the control scaffolds. Osteocalcin gene expression was upregulated in presence of PL during all culture period, which indicates an enhanced osteogenic induction. These results suggest the synergistic effect of PL and hASCs in combinatory TE strategies and support the potential of PL to increase the multifunctionality of the 3D hybrid construct for bone TE applications.

  2. BIRM 270: a novel inhibitor of arachidonate release that blocks leukotriene B4 and platelet-activating factor biosynthesis in human neutrophils.

    Science.gov (United States)

    Farina, P R; Graham, A G; Hoffman, A F; Watrous, J M; Borgeat, P; Nadeau, M; Hansen, G; Dinallo, R M; Adams, J; Miao, C K

    1994-12-01

    (S)-N-[2-Cyclohexyl-1-(2-pyridinyl)ethyl]-5-methyl-2-benzoxazolamine+ ++ (BIRM 270) was identified as a potent and enantiomerically selective inhibitor of calcium ionophore A23187-stimulated leukotriene B4 biosynthesis in human neutrophils. The (S)- and (R)-enantiomers exhibited IC50 values of 1 nM and 40 nM, respectively. BIRM 270 did not inhibit 5-lipoxygenase activity in a cell-free assay. In addition, the compound did not interfere with the conversion of exogenous 5-lipoxygenase substrate (15S)-hydroperoxyeicosatetraenoic acid to (5S, 15S)-dihydroxyeicosatetraenoic acid in intact, ionophore-stimulated neutrophils. Under the same experimental conditions, BIRM 270 inhibited the production of 5-lipoxygenase products from endogenous substrate, suggesting that the compound affected arachidonate availability rather than metabolism. Consistent with this concept, the inhibition of leukotriene B4 biosynthesis by BIRM 270 was overcome by the addition of exogenous arachidonic acid to the leukocyte preparation. Direct measurement of free arachidonate by gas chromatography-mass spectrometry confirmed that BIRM 270 inhibited arachidonate release from ionophore-stimulated neutrophils. The compound did not affect arachidonate reacylation. The blockage of arachidonate release coincided with inhibition of leukotriene B4 biosynthesis in these cells. BIRM 270 also inhibited ionophore-stimulated platelet-activating factor biosynthesis by human neutrophils. Although these results suggest that BIRM 270 inhibited phospholipase A2-mediated deacylation of membrane phospholipids, the compound did not directly inhibit the high molecular weight, cytosolic phospholipase A2 derived from human neutrophils or U937 cells. Thus, suppression of arachidonate mobilization by BIRM 270 may be due to indirect inhibition of intracellular phospholipase A2 or to inhibition of another acylhydrolase activity.

  3. Pharmacological inhibition of eicosanoids and platelet-activating factor signaling impairs zymosan-induced release of IL-23 by dendritic cells.

    Science.gov (United States)

    Rodríguez, Mario; Márquez, Saioa; Montero, Olimpio; Alonso, Sara; Frade, Javier García; Crespo, Mariano Sánchez; Fernández, Nieves

    2016-02-15

    The engagement of the receptors for fungal patterns induces the expression of cytokines, the release of arachidonic acid, and the production of PGE2 in human dendritic cells (DC), but few data are available about other lipid mediators that may modulate DC function. The combined antagonism of leukotriene (LT) B4, cysteinyl-LT, and platelet-activating factor (PAF, 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) inhibited IL23A mRNA expression in response to the fungal surrogate zymosan and to a lower extent TNFA (tumor necrosis factor-α) and CSF2 (granulocyte macrophage colony-stimulating factor) mRNA. The combination of lipid mediators and the lipid extract of zymosan-conditioned medium increased the induction of IL23A by LPS (bacterial lipopolysaccharide), thus suggesting that unlike LPS, zymosan elicits the production of mediators at a concentration enough for optimal response. Zymosan induced the release of LTB4, LTE4, 12-hydroxyeicosatetraenoic acid (12-HETE), and PAF C16:0. DC showed a high expression and detectable Ser663 phosphorylation of 5-lipoxygenase in response to zymosan, and a high expression and activity of LPCAT1/2 (lysophosphatidylcholine acyltransferase 1 and 2), the enzymes that incorporate acetate from acetyl-CoA into choline-containing lysophospholipids to produce PAF. Pharmacological modulation of the arachidonic acid cascade and the PAF receptor inhibited the binding of P-71Thr-ATF2 (activating transcription factor 2) to the IL23A promoter, thus mirroring their effects on the expression of IL23A mRNA and IL-23 protein. These results indicate that LTB4, cysteinyl-LT, and PAF, acting through their cognate G protein-coupled receptors, contribute to the phosphorylation of ATF2 and play a central role in IL23A promoter trans-activation and the cytokine signature induced by fungal patterns.

  4. A reaction-diffusion model of the Darien Gap Sterile Insect Release Method

    Science.gov (United States)

    Alford, John G.

    2015-05-01

    The Sterile Insect Release Method (SIRM) is used as a biological control for invasive insect species. SIRM involves introducing large quantities of sterilized male insects into a wild population of invading insects. A fertile/sterile mating produces offspring that are not viable and the wild insect population will eventually be eradicated. A U.S. government program maintains a permanent sterile fly barrier zone in the Darien Gap between Panama and Columbia to control the screwworm fly (Cochliomyia Hominivorax), an insect that feeds off of living tissue in mammals and has devastating effects on livestock. This barrier zone is maintained by regular releases of massive quantities of sterilized male screwworm flies from aircraft. We analyze a reaction-diffusion model of the Darien Gap barrier zone. Simulations of the model equations yield two types of spatially inhomogeneous steady-state solutions representing a sterile fly barrier that does not prevent invasion and a barrier that does prevent invasion. We investigate steady-state solutions using both phase plane methods and monotone iteration methods and describe how barrier width and the sterile fly release rate affects steady-state behavior.

  5. NOSH-sulindac (AVT-18A) is a novel nitric oxide- and hydrogen sulfide-releasing hybrid that is gastrointestinal safe and has potent anti-inflammatory, analgesic, antipyretic, anti-platelet, and anti-cancer properties

    OpenAIRE

    Kashfi, Khosrow; Chattopadhyay, Mitali; Kodela, Ravinder

    2015-01-01

    Sulindac is chemopreventive and has utility in patients with familial adenomatous polyposis; however, side effects preclude its long-term use. NOSH-sulindac (AVT-18A) releases nitric oxide and hydrogen sulfide, was designed to be a safer alternative. Here we compare the gastrointestinal safety, anti-inflammatory, analgesic, anti-pyretic, anti-platelet, and anti-cancer properties of sulindac and NOSH-sulindac administered orally to rats at equimolar doses. Gastrointestinal safety: 6 h post-adm...

  6. Cyclosporine A enhances platelet aggregation.

    Science.gov (United States)

    Grace, A A; Barradas, M A; Mikhailidis, D P; Jeremy, J Y; Moorhead, J F; Sweny, P; Dandona, P

    1987-12-01

    In view of the reported increase in thromboembolic episodes following cyclosporine A (CyA) therapy, the effect of this drug on platelet aggregation and thromboxane A2 release was investigated. The addition of CyA, at therapeutic concentrations to platelet rich plasma from normal subjects in vitro was found to increase aggregation in response to adrenaline, collagen and ADP. Ingestion of CyA by healthy volunteers was also associated with enhanced platelet aggregation. The CyA-mediated enhancement of aggregation was further enhanced by the addition in vitro of therapeutic concentrations of heparin. Platelets from renal allograft recipients treated with CyA also showed hyperaggregability and increased thromboxane A2 release, which were most marked at "peak" plasma CyA concentration and less so at "trough" concentrations. Platelet hyperaggregability in renal allograft patients on long-term CyA therapy tended to revert towards normal following the replacement of CyA with azathioprine. Hypertensive patients with renal allografts on nifedipine therapy had normal platelet function and thromboxane release in spite of CyA therapy. These observations suggest that CyA-mediated platelet activation may contribute to the pathogenesis of the thromboembolic phenomena associated with the use of this drug. The increased release of thromboxane A2 (a vasoconstrictor) may also play a role in mediating CyA-related nephrotoxicity.

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

    Directory of Open Access Journals (Sweden)

    Silva Raul F

    2012-07-01

    Full Text Available Abstract 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 1 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 effect for clinical or experimental use as a

  8. An inhibitor selective for collagen-stimulated platelet aggregation from the salivary glands of hard tick Haemaphysalis longicornis and its mechanism of action

    Institute of Scientific and Technical Information of China (English)

    程远国; 吴厚永; 李德昌

    1999-01-01

    Soluble materials of salivary glands from Haemaphysalis longicornis were found to inhibit collagen, ADP, and thrombin-stimulated platelet aggregation. One inhibitory component was purified to salivary gland homogeneity by a combination of gel filtration, ion-exchange, and C8 reverse phase HPLC. The purified activity, named longieornin, is a protein of moleeular weight 16 000 on SDS-PAGE under both reduced and nonredueed conditions. Collagen-mediated aggregation of platelets in plasma and of washed platelets (IC50 was approximately 60 nmol/L) was inhibited with the same efficacy. No inhibition of aggregation stimulated by other effeetors, including ADP, arachidonic acid, thrombin, ristocetin, calcium ionophore A23187, thromboxane A2 mimetic U46619 and 12-O-phorbol-13-myristate acetate, was observed. Longieonin had no effect on platelet adhension to collagen. Not only platelet aggregation but also release reaction, and increase of intraeellar Ca2+ level of platelets in response to collagen were com

  9. Platelet proteomics.

    Science.gov (United States)

    Zufferey, Anne; Fontana, Pierre; Reny, Jean-Luc; Nolli, Severine; Sanchez, Jean-Charles

    2012-01-01

    Platelets are small cell fragments, produced by megakaryocytes, in the bone marrow. They play an important role in hemostasis and diverse thrombotic disorders. They are therefore primary targets of antithrombotic therapies. They are implicated in several pathophysiological pathways, such as inflammation or wound repair. In blood circulation, platelets are activated by several pathways including subendothelial matrix and thrombin, triggering the formation of the platelet plug. Studying their proteome is a powerful approach to understand their biology and function. However, particular attention must be paid to different experimental parameters, such as platelet quality and purity. Several technologies are involved during the platelet proteome processing, yielding information on protein identification, characterization, localization, and quantification. Recent technical improvements in proteomics combined with inter-disciplinary strategies, such as metabolomic, transcriptomics, and bioinformatics, will help to understand platelets biological mechanisms. Therefore, a comprehensive analysis of the platelet proteome under different environmental conditions may contribute to elucidate complex processes relevant to platelet function regarding bleeding disorders or platelet hyperreactivity and identify new targets for antiplatelet therapy.

  10. Exchange Reaction Between Selenite and Hydroxyl Ion of Variable Charge Soil Surfaces: Ⅱ. Kinetics of Hydroxyl Release

    Institute of Scientific and Technical Information of China (English)

    ZHOU Shi-Wei; ZHANG Gang-Ya; ZHANG Xiao-Nian

    2003-01-01

    A self-made constant pH automated titration instrument was used to study the kinetics of hydroxyl release during selenite reacting with variable charge soils. The rate of hydroxyl release was very rapid at the first several minutes, then gradually slowed down, and at last did not change any more. The experimental data was well fitted by the Langmuir kinetic equation, and with increasing selenite concentration or decreasing solution pH, the reaction lasted longer, the maximum of hydroxyl release (xm) increased, and the binding constant (k) decreased. The time of hydroxyl release with Xuwen latosol was much longer than that with Jinxian red soil.

  11. Scanning electrochemical microscopy of metallic biomaterials: reaction rate and ion release imaging modes.

    Science.gov (United States)

    Gilbert, J L; Smith, S M; Lautenschlager, E P

    1993-11-01

    The Scanning Electrochemical Microscope (SECM) is a nonoptical scanning microscopic instrument capable of imaging highly localized electrical currents associated with charge transfer reactions on metallic biomaterials surfaces. The SECM operates as an aqueous electrochemical cell under bipotentiostatic control with a microelectrode and sample independently biased as working electrodes. Microelectrode current and position is recorded as it is scanned very near a metallurgically polished planar sample surface. To date, the SECM has imaged metallic biomaterials surfaces in oxygen reaction rate imaging (ORRI) and ion release and deposition imaging (IRDI) modes. In ORRI, sample and microelectrode are biased at sufficiently negative potentials to reduce absorbed oxygen. As the microelectrode scans areas of active oxygen reduction, localized diffusion fields with decreased oxygen solution concentrations are encountered and resultant decrements in microelectrode current are observed. In IRDI mode the sample is positively biased and the microelectrode is negatively biased. The microelectrode detects anodic dissolution products with highest currents being observed over the most active areas. Performance of the SECM has been evaluated on Ni minigrids, gamma-1 Hg-Ag dental amalgam crystals, and sintered beads of Co-Cr-Mo alloy which represent significantly different geometries and corrosion processes to help demonstrate the potential of this instrument. The SECM is a valuable tool for imaging microelectrochemical processes on the surfaces of metallurgically polished metallic biomaterials samples and a wide variety of other surfaces of biological interest where charge transfer reactions occur. The SECM allows selective biasing of metallic biomaterials surfaces and Faradaic reactions can be selectively imaged while the surface is in the active, passive, or transpassive state.

  12. Platelet lipidomic.

    Science.gov (United States)

    Dolegowska, B; Lubkowska, A; De Girolamo, L

    2012-01-01

    Lipids account for 16-19 percent dry platelet matter and includes 65 percent phospholipids, 25 percent neutral lipids and about 8 percent glycosphingolipids. The cell membrane that surrounds platelets is a bilayer that contains different types phospholipids symmetrically distributed in resting platelets, such as phosphatidylserine (PS), phosphatidylethanolamine (PE), phosphatidylcholine, and sphingomyelin. The collapse of lipid asymmetry is exposure of phosphatidylserine in the external leaflet of the plasma bilayer, where it is known to serve at least two major functions: providing a platform for development of the blood coagulation cascade and presenting the signal that induces phagocytosis of apoptotic cells. During activation, this asymmetrical distribution becomes disrupted, and PS and PE become exposed on the cell surface. The transbilayer movement of phosphatidylserine is responsible for the platelet procoagulant activity. Exposure of phosphatidylserine is a flag for macrophage recognition and clearance from the circulation. Platelets, stored at room temperature for transfusion for more than 5 days, undergo changes collectively known as platelet storage lesions. Thus, the platelet lipid composition and its possible modifications over time are crucial for efficacy of platelet rich plasma therapy. Moreover, a number of substances derived from lipids are contained into platelets. Eicosanoids are lipid signaling mediators generated by the action of lipoxygenase and include prostaglandins, thromboxane A2, 12-hydroxyeicosatetraenoic acid. Isoprostanes have a chemical structure similar to this of prostanoids, but are differently produced into the particle, and are ligands for prostaglandins receptors, exhibiting biological activity like thromboxane A2. Endocannabinoids are derivatives from arachidonic acid which could reduce local pain. Phospholipids growth factors (sphingolipids, lysophosphatidic acid, platelet-activating factor) are involved in tissue

  13. Platelets Inhibit Migration of Canine Osteosarcoma Cells.

    Science.gov (United States)

    Bulla, S C; Badial, P R; Silva, R C; Lunsford, K; Bulla, C

    2017-01-01

    The interaction between platelets and tumour cells is important for tumour growth and metastasis. Thrombocytopenia or antiplatelet treatment negatively impact on cancer metastasis, demonstrating potentially important roles for platelets in tumour progression. To our knowledge, there is no information regarding the role of platelets in cancer progression in dogs. This study was designed to test whether canine platelets affected the migratory behaviour of three canine osteosarcoma cell lines and to give insights of molecular mechanisms. Intact platelets, platelet lysate and platelet releasate inhibited the migration of canine osteosarcoma cell lines. Addition of blood leucocytes to the platelet samples did not alter the inhibitory effect on migration. Platelet treatment also significantly downregulated the transcriptional levels of SNAI2 and TWIST1 genes. The interaction between canine platelets or molecules released during platelet activation and these tumour cell lines inhibits their migration, which suggests that canine platelets might antagonize metastasis of canine osteosarcoma. This effect is probably due to, at least in part, downregulation of genes related to epithelial-mesenchymal transition. Copyright © 2016. Published by Elsevier Ltd.

  14. A reaction-diffusion model of ROS-induced ROS release in a mitochondrial network.

    Directory of Open Access Journals (Sweden)

    Lufang Zhou

    2010-01-01

    Full Text Available Loss of mitochondrial function is a fundamental determinant of cell injury and death. In heart cells under metabolic stress, we have previously described how the abrupt collapse or oscillation of the mitochondrial energy state is synchronized across the mitochondrial network by local interactions dependent upon reactive oxygen species (ROS. Here, we develop a mathematical model of ROS-induced ROS release (RIRR based on reaction-diffusion (RD-RIRR in one- and two-dimensional mitochondrial networks. The nodes of the RD-RIRR network are comprised of models of individual mitochondria that include a mechanism of ROS-dependent oscillation based on the interplay between ROS production, transport, and scavenging; and incorporating the tricarboxylic acid (TCA cycle, oxidative phosphorylation, and Ca(2+ handling. Local mitochondrial interaction is mediated by superoxide (O2.- diffusion and the O2.(--dependent activation of an inner membrane anion channel (IMAC. In a 2D network composed of 500 mitochondria, model simulations reveal DeltaPsi(m depolarization waves similar to those observed when isolated guinea pig cardiomyocytes are subjected to a localized laser-flash or antioxidant depletion. The sensitivity of the propagation rate of the depolarization wave to O(2.- diffusion, production, and scavenging in the reaction-diffusion model is similar to that observed experimentally. In addition, we present novel experimental evidence, obtained in permeabilized cardiomyocytes, confirming that DeltaPsi(m depolarization is mediated specifically by O2.-. The present work demonstrates that the observed emergent macroscopic properties of the mitochondrial network can be reproduced in a reaction-diffusion model of RIRR. Moreover, the findings have uncovered a novel aspect of the synchronization mechanism, which is that clusters of mitochondria that are oscillating can entrain mitochondria that would otherwise display stable dynamics. The work identifies the

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

    Science.gov (United States)

    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.

  16. Platelets: bridging hemostasis, inflammation, and immunity.

    Science.gov (United States)

    Jenne, C N; Urrutia, R; Kubes, P

    2013-06-01

    Although the function of platelets in the maintenance of hemostasis has been studied in great detail, more recent evidence has highlighted a central role for platelets in the host inflammatory and immune responses. Platelets by virtue of their large numbers and their ability to rapidly release a broad spectrum of immunomodulatory cytokines, chemokines, and other mediators act as circulating sentinels. Upon detection of a pathogen, platelets quickly activate and begin to drive the ensuing inflammatory response. Platelets have the ability to directly modulate the activity of neutrophils (phagocytosis, oxidative burst), endothelium (adhesion molecule and chemokine expression), and lymphocytes. Due to their diverse array of adhesion molecules and preformed chemokines, platelets are able to adhere to leukocytes and facilitate their recruitment to sites of tissue damage or infection. Furthermore, platelets directly participate in the capture and sequestration of pathogens within the vasculature. Platelet-neutrophil interactions are known to induce the release of neutrophil extracellular traps (NETs) in response to either bacterial or viral infection, and platelets have been shown to internalize pathogens, sequestering them in engulfment vacuoles. Finally, emerging data indicate that platelets also participate in the host immune response by directly killing infected cells. This review will highlight the central role platelets play in the initiation and modulation of the host inflammatory and immune responses.

  17. Acquired platelet function defect

    Science.gov (United States)

    Acquired qualitative platelet disorders; Acquired disorders of platelet function ... blood clotting. Disorders that can cause problems in platelet function include: Idiopathic thrombocytopenic purpura Chronic myelogenous leukemia Multiple ...

  18. Platelet Donation

    Science.gov (United States)

    ... of gratitude that washed over me when I saw those platelets going into my husband’s body. I ... Needles LGBTQ+ Donors Blood Donor Community SleevesUp Games Facebook Avatars and Badges Banners eCards Red Cross Information ...

  19. Salvianolic acid B inhibits platelets-mediated inflammatory response in vascular endothelial cells.

    Science.gov (United States)

    Xu, Shixin; Zhong, Aiqin; Bu, Xiaokun; Ma, Huining; Li, Wei; Xu, Xiaomin; Zhang, Junping

    2015-01-01

    Salvianolic acid B (SAB) is a hydrophilic component isolated from the Chinese herb Salviae miltiorrhizae, which has been used clinically for the treatment of ischemic cardiovascular and cerebrovascular diseases. Platelets-mediated vascular inflammatory response contributes to the initiation and progression of atherosclerosis. In this paper, we focus on the modulating effects of SAB on the inflammatory reaction of endothelial cells triggered by activated platelets. Human umbilical vein endothelial cells (EA.hy926) were pretreated with SAB followed by co-culture with ADP-activated platelets. Adhesion of platelets to endothelial cells was observed by amorphological method. The activation of nuclear factor-kappa B was evaluated by NF-κB p65 nuclear translocation and the protein phosphorylation. A determination of the pro-inflammatory mediators (ICAM-1, IL-1β, IL-6, IL-8, MCP-1) mRNA and protein were also conducted. In addition, the inhibitory effects of SAB on platelets activation were also evaluated using a platelet aggregation assay and assessing the release level of soluble P-selectin. The results showed that SAB dose-dependently inhibited ADP- or α-thrombin-induced human platelets aggregation in platelet rich plasma (PRP) samples, and significantly decreased soluble P-selectin release from both agonists stimulated washed platelets. It was also found that pre-treatment with SAB reduced adhesion of ADP-activated platelets to EA.hy926 cells and inhibited NF-κB activation. In addition, SAB significantly suppressed pro-inflammatory mediators mRNA and protein in EA.hy926 cells in a dose-dependent manner. These results indicated that, in addition to its inhibitory effects on platelets activation, SAB was able to attenuate platelets-mediated inflammatory responses in endothelial cells even if the platelets had already been activated. This anti-inflammatory effect was related to the inhibition of NF-κB activation. Our findings suggest that SAB may be a potential

  20. Utilizing light-triggered plasmon-driven catalysis reactions as a template for molecular delivery and release.

    Science.gov (United States)

    Gu, Xin; Wang, Huan; Camden, Jon P

    2017-09-01

    Due to the facile manipulation and non-invasive nature of light-triggered release, it is one of the most potent ways to selectively and remotely deliver a molecular target. Among the various carrier platforms, plasmonic nanoparticles possess advantages such as enhanced cellular uptake and easy loading of "cargo" molecules. Two general strategies are currently utilized to achieve light-induced molecule release from plasmonic nanoparticles. The first uses femtosecond laser pulses to directly break the bond between the nanoparticle and the loaded target. The other requires significant photo-thermal effects to weaken the interaction between the cargo molecules and nanoparticle-attached host molecules. Different from above mechanisms, herein, we introduce a new light-controlled molecular-release method by taking advantage of a plasmon-driven catalytic reaction at the particle surface. In this strategy, we link the target to a plasmon responsive molecule, 4-aminobenzenethiol (4-ABT), through the robust and simple EDC coupling reaction and subsequently load the complex onto the particles via the strong Au-thiol interaction. Upon continuous-wave (CW) laser illumination, the excited surface plasmon catalyzes the formation of 4,4'-dimercaptoazobenzenethiol (DMAB) and simultaneously releases the loaded molecules with high efficiency. This method does not require the use of high-power pulsed lasers, nor does it rely on photo-thermal effects. We believe that plasmon-driven release strategies open a new direction for the designing of next-generation light-triggered release processes.

  1. 富血小板纤维蛋白体外释放生长因子相关因素的研究%Rich platelet fibrin release of growth factors in vitro study of the relationship with temperature

    Institute of Scientific and Technical Information of China (English)

    李艳秋; 刘金凤; 张天首; 张海鑫; 徐云

    2016-01-01

    目的:观察保存温度及离心管的材质在制备富血小板纤维体外释放生长因子中发挥的作用,优化富血小板纤维蛋白的提取方法。方法:采集志愿者的静脉血,分别使用玻璃材质的离心管和塑料材质的离心管进行离心,制备完成后将收集到的PRF分别置于4℃和37℃的环境中进行保存,收集PRF所释放的生长因子,比较不同方法得到的富血小板纤维蛋白释放的血小板衍生生长因子-AB (platelet-derived growth factor, PDGF-AB)、转化生长因子-β(transforming growth factor-β, TGF-β)的量的差异。结果:使用玻璃试管组的PRF释放的PDGF-AB和TGF-β的量高于对照组,存放于4℃条件的PRF释放的生长因子高于对照组。结论:在制备PRF时,建议使用玻璃材质的离心管储存于4℃左右的环境中,以便PRF发挥更好地促进组织生长于修复的作用。%Objective: Observation of preservation temperature and centrifugal pipe material in the prepara-tion of platelet rich fiber in vitro release of growth factors play a role ,to optimize the extraction methods of rich platelet fibrin. Method: Venous blood collection and volunteers, using glass centrifugal cen-trifuge tube and plastic centrifuge tube, after the completion of the preparation of the collected PRF re-spectively at 4 ℃ and 37 ℃ to save, collect PRF release of growth factors, to compare different ways to get rich platelet fibrin release of platelet-derived growth factor-AB (platelet-derived growth factor, PDGF-AB), transforming growth factor beta (transforming growth factor beta, TGF-beta) the amount of difference. Result:Use glass tube group PRF release PDGF-AB and TGF-the amount of beta is higher than the control group, stored at 4℃condition of PRF release of growth factor is higher than the control group. Conclusion: In the preparation of PRF, it is recommended to use glass centrifugal pipe stored at 4℃about environment, in

  2. Experimental elaboration of faulting induced by fluid-releasing mineral reactions in subduction zones

    Science.gov (United States)

    Green, H.; Zhang, J.; Jung, H.; Dobrzinetskaya, L.

    2003-04-01

    Dehydration embrittlement has been cited repeatedly as a potential mechanism for triggering earthquakes at depths where unassisted brittle failure is impossible due to the normal-stress-dependence of friction. We are investigating two different aspects of this problem in the laboratory: (i) dehydration of antigorite under stress where the ΔV of reaction varies from strongly positive to distinctly negative; (ii) deformation of eclogite in which the nominally anhydrous minerals contain small amounts of dissolved H_2O that can lead to faulting induced by very small amounts of melting stimulated by exsolution of H_2O. (i) Antigorite has the largest stability field of the serpentines and is often cited as potentially being the source of most or all mantle earthquakes to a depth of over 200 km. However, like other low-pressure hydrous phases, the net volume change accompanying antigorite dehydration varies from strongly positive at low P to negative at P > ˜2-2.5 GPa. Fracture mechanics theory predicts that dehydration should not induce shear failure if ΔV<0. To test the effect of ΔV on faulting, we have deformed an extensively-serpentinized peridotite at P = 1-6 GPa. We conducted constant strain rate experiments in a Griggs-type apparatus at P = 1.0 - 3.4 GPa and rapid-pumping experiments in a Walker-type multianvil apparatus, culminating in pressures as high as 6 GPa. Independent of the sign of ΔV, specimens subjected to stress during dehydration yielded extremely thin zones of reaction products with shear offset across them. Some were clearly faults whereas others could be precursors to faulting. Fluid released at grain boundaries between antigorite and relict olivine locally produced Mode I cracks &fluid inclusions. (ii) Deformation of "wet" eclogite at 3 GPa and temperatures between the wet and dry solidi induced exsolution of H_2O and formation of very small amounts (<1%) of melt, leading to faulting. At lower temperature the rock was extremely strong but

  3. A smart hydrogel-based time bomb triggers drug release mediated by pH-jump reaction

    Directory of Open Access Journals (Sweden)

    Prapatsorn Techawanitchai, Naokazu Idota, Koichiro Uto, Mitsuhiro Ebara and Takao Aoyagi

    2012-01-01

    Full Text Available We demonstrate a timed explosive drug release from smart pH-responsive hydrogels by utilizing a phototriggered spatial pH-jump reaction. A photoinitiated proton-releasing reaction of o-nitrobenzaldehyde (o-NBA was integrated into poly(N-isopropylacrylamide-co-2-carboxyisopropylacrylamide (P(NIPAAm-co-CIPAAm hydrogels. o-NBA-hydrogels demonstrated the rapid release of protons upon UV irradiation, allowing the pH inside the gel to decrease to below the pKa value of P(NIPAAm-co-CIPAAm. The generated protons diffused gradually toward the non-illuminated area, and the diffusion kinetics could be controlled by adjusting the UV irradiation time and intensity. After irradiation, we observed the enhanced release of entrapped L-3,4-dihydroxyphenylalanine (DOPA from the gels, which was driven by the dissociation of DOPA from CIPAAm. Local UV irradiation also triggered the release of DOPA from the non-illuminated area in the gel via the diffusion of protons. Conventional systems can activate only the illuminated region, and their response is discontinuous when the light is turned off. The ability of the proposed pH-jump system to permit gradual activation via proton diffusion may be beneficial for the design of predictive and programmable devices for drug delivery.

  4. Contribution of neutron-capture reactions in energy release in the fuel core of BN-600

    Science.gov (United States)

    Bahdanovich, R. B.; Romanenko, V. I.; Tikhomirov, G. V.

    2017-01-01

    The use of modern computing powers and calculation methods allows to get closer to reality results of modelling, as well as to explore areas inaccessible to the experiment. Until now, the calculation of the energy released from the capture of neutrons in the reactor core has been given little attention. The method for calculation of the effective energy release components in a nuclear reactor allows to specify the values used by engineering programs for capture energy release in fast reactors. The paper presents improved method and the results of calculation of three models of the reactor BN-600. It is shown that the contribution of capture energy release in effective energy release for fresh fuel is equal to 4%, which is more than for VVER reactors. During the calculation we created a simple calculation model of the fast reactor, considering its features.

  5. Platelet activation patterns in platelet size sub-populations: differential responses to aspirin in vitro.

    Science.gov (United States)

    Mangalpally, Kiran Kumar R; Siqueiros-Garcia, Alan; Vaduganathan, Muthiah; Dong, Jing-Fei; Kleiman, Neal S; Guthikonda, Sasidhar

    2010-10-01

    Circulating platelets are heterogeneous in size and structure. Whether this translates into differences in platelet function and efficacy of antiplatelet therapy is unclear. Hence, we decided to investigate the activation patterns among different platelet populations differentiated by size, and to compare the inhibitory effects of aspirin in these populations. Circulating platelets from 9 healthy volunteers were separated by size and stratified into the largest and smallest quintiles. Platelets were stimulated with 75 μM arachidonic acid (AA), 10 μM ADP or 25 μM TRAP. Alpha-granule protein secretion and expression (P-selectin, VWF, fibrinogen), surface-protein activation (activated integrin αIIbβ3) were assessed. Platelet thromboxane B(2) (TxB(2)) synthesis following AA stimulation was measured in vitro before and after incubation with 265 μM aspirin. Reticulated (juvenile) platelets were assessed using thiazole orange staining. A greater number of large platelets in the largest quintile were reticulated compared with the smallest quintile (6.1 ± 2.8% vs. 1.2 ± 1.5% respectively, p aspirin (1029 ± 190 pg/mL vs. 851 ± 159 pg/mL, respectively, p = 0.03). After stimulation with each agonist, a greater proportion of large platelets bound fibrinogen, VWF, P-selectin and activated integrin αIIbβ3 than small platelets both in the presence and in the absence of in vitro aspirin. In an in vitro setting, large platelets appear to be more active than small platelets and continue to be more active even after in vitro aspirin. Platelets exhibit heterogeneity in size and structure. Whether this translates into platelet function and efficacy of antiplatelet therapy is unclear. We evaluated platelet functional properties and the effects of aspirin on separated platelet subpopulations in an in vitro setting. Platelets were sorted into the largest and smallest size quintiles using flow cytometry forward scatter. Alpha-granule protein release, dense granule content

  6. Inflammatory factor release from leukocyte-and platelet-rich plasma gel%富白细胞-血小板血浆凝胶释放的炎性生长因子*★

    Institute of Scientific and Technical Information of China (English)

    温天杨; 王爱红; 许樟荣

    2013-01-01

    BACKGROUND: Current studies about leukocyte- and platelet-rich plasma gel mainly focus on growth factor release and the mechanism underlying promoting tissue growth and wound healing. OBJECTIVE:To investigate the mechanism of leukocyte-and platelet-rich plasma gel by measuring the levels of interleukin-1, interleukin-4, interleukin-6, platelet-derived growth factor-BB, transforming growth factor-β1, and vascular endothelial growth factor released from leukocyte- and platelet-rich plasma gel and observing the ultrastructure of leukocyte-and platelet-rich plasma gel. METHODS:Blood samples were col ected from 12 healthy volunteers. Leukocyte-and platelet-rich plasma was produced by two-step centrifugation, and leukocyte-and platelet-rich plasma gel was obtained by combining the leukocyte-and platelet-rich plasma with thrombin and calcium gluconate (10:1). The leukocyte-and platelet-rich plasma gel was preserved in Dulbecco’s modified Eagle’s medium, and the Dulbecco’s modified Eagle’s medium including exudates of leukocyte-and platelet-rich plasma gel was col ected at days 1, 3, 7, 14, 21. RESULTS AND CONCLUSION:Enzyme linked immunoabsorbent assay showed that the leukocyte formula in the leukocyte-and platelet-rich plasma gel was different from that in the whole blood, and lymphocytes shared the largest proportion. Interleukin-1 level peaked at 0-1 day of culture (P  目的:通过测定富白细胞-血小板血浆凝胶中释放的白细胞介素1,4,6和血小板源性生长因子BB、转化生长因子β、血管内皮生长因子的水平,观察富白细胞-血小板血浆凝胶超微结构,对其抗菌作用和促进溃疡愈合的作用机制进行进一步探讨。  方法:取健康志愿者空腹静脉血离心、分离得到富白细胞-血小板血浆,再以10∶1的比例加入激活剂后混匀得富白细胞-血小板血浆凝胶。将凝胶保存在DMEM培养基中,分别于培养1,3,7,14,21 d后收集含有渗出

  7. Platelet-TLR7 mediates host survival and platelet count during viral infection in the absence of platelet-dependent thrombosis.

    Science.gov (United States)

    Koupenova, Milka; Vitseva, Olga; MacKay, Christopher R; Beaulieu, Lea M; Benjamin, Emelia J; Mick, Eric; Kurt-Jones, Evelyn A; Ravid, Katya; Freedman, Jane E

    2014-07-31

    Viral infections have been associated with reduced platelet counts, the biological significance of which has remained elusive. Here, we show that infection with encephalomyocarditis virus (EMCV) rapidly reduces platelet count, and this response is attributed to platelet Toll-like receptor 7 (TLR7). Platelet-TLR7 stimulation mediates formation of large platelet-neutrophil aggregates, both in mouse and human blood. Intriguingly, this process results in internalization of platelet CD41-fragments by neutrophils, as assessed biochemically and visualized by microscopy, with no influence on platelet prothrombotic properties. The mechanism includes TLR7-mediated platelet granule release, translocation of P-selectin to the cell surface, and a consequent increase in platelet-neutrophil adhesion. Viral infection of platelet-depleted mice also led to increased mortality. Transfusion of wild-type, TLR7-expressing platelets into TLR7-deficient mice caused a drop in platelet count and increased survival post EMCV infection. Thus, this study identifies a new link between platelets and their response to single-stranded RNA viruses that involves activation of TLR7. Finally, platelet-TLR7 stimulation is independent of thrombosis and has implications to the host immune response and survival.

  8. 21 CFR 864.7040 - Adenosine triphosphate release assay.

    Science.gov (United States)

    2010-04-01

    ... device that measures the release of adenosine triphosphate (ATP) from platelets following aggregation. This measurement is made on platelet-rich plasma using a photometer and a luminescent firefly extract. Simultaneous measurements of platelet aggregation and ATP release are used to evaluate platelet...

  9. Small RNAs as potential platelet therapeutics.

    Science.gov (United States)

    Edelstein, Leonard C; Bray, Paul F

    2012-01-01

    MicroRNAs (miRNAs) are 21-23 nucleotide RNAs that regulate more than 60% of mammalian protein coding genes. miRNAs play critical roles in hematopoiesis and megakaryocyte function and development. Platelets, in addition to possessing functional miRNA processing machinery, have miRNA levels that have been correlated with platelet reactivity, and these miRNAs have been shown to target mRNAs that encode proteins that alter platelet function. There are potential uses of platelet miRNA as biomarkers and therapeutic agents. Due to the ability of platelets to release miRNA-containing microparticles at sites of activation, including angiogenic regions, tumors, and atherosclerotic plaques, there is the possibility of engineering platelets to deliver miRNA-based therapies to these sites. Cellpreferential expression of miRNAs could be exploited to restrict transgene expression in hematopoietic stem cell gene therapy to the desired lineage, including megakaryocytes and platelets. Finally, manipulation of gene expression in stored platelets may allow more effective platelet storage. Although much work remains to be done, there is great potential in miRNA-based platelet therapies.

  10. Platelet aggregation responses vary over a period of time in healthy controls.

    Science.gov (United States)

    Refaai, Majed A; Frenkel, Eugene; Sarode, Ravi

    2010-01-01

    Platelet aggregation study is performed to investigate platelet function abnormality. A normal healthy control sample is usually run with the patient sample as a quality control measure. At our institution, we observed variations in platelet aggregation responses in our normal repeat controls. Therefore, we analysed aggregation parameters in these controls. Whole blood aggregation studies were performed with adenosine diphosphate (ADP), arachidonic acid (AA), collagen and ristocetin. Adenosine triphosphate (ATP) secretion was also measured simultaneously by leuciferin-leuciferase reaction. During a 5-year period, a total of 86 studies were performed on seven controls. Aggregations were within the acceptable range in 67% of the time. Collagen was the most affected agonist in our study. On five occasions, four controls had subnormal aggregations with two agonists. All abnormal responses were hypoaggregation except for two who had hyperaggregation with collagen and AA. Only one out of seven controls was always normal. In the presence of a subnormal control result, a new control was run before releasing the patient's platelet aggregation results. These findings suggest that many physiological factors, other than medications, may affect platelet function even in normal individuals. Therefore, a repeat study at a later date to demonstrate a reproducible abnormality would be prudent before labeling a patient's platelets abnormal.

  11. The origin and function of platelet glycosyltransferases

    DEFF Research Database (Denmark)

    Wandall, Hans H; Rumjantseva, Viktoria; Sørensen, Anne Louise Tølbøll;

    2012-01-01

    Platelets are megakaryocyte subfragments that participate in hemostatic and host defense reactions and deliver pro- and anti-angiogenic factors throughout the vascular system. Platelets are anucleated cells and lack a complex secretory apparatus with distinct Golgi/endoplasmic reticulum compartme...

  12. Hereditary sideroblastic anemia with associated platelet abnormalities.

    Science.gov (United States)

    Soslau, G; Brodsky, I

    1989-12-01

    A 62 year old male (R.H.) presented with a mild anemia (Hb 11-12 gm%) and a history of multiple hemorrhagic episodes. The marrow had 40-50% sideroblasts. Marrow chromosomes were normal. His wife was hematologically normal, while one daughter, age 30 years, had a sideroblastic anemia (Hb 11-12 gm%) with 40-50% sideroblasts in the marrow. Her anemia was first noted at age 15 years. Administration of vitamin B6 did not correct the anemia in either the father or daughter. Platelet abnormalities inherited jointly with this disorder are described for the first time. Both R.H. and his daughter had prolonged bleeding times, with normal PTT, PT times, fVIII:C, fVIII:Ag levels, and vWF multimers, which may rule out a von Willebrand's disease. They have normal platelet numbers but abnormally low platelet adhesiveness and greatly depressed ADP, collagen, and epinephrine responsiveness. Response to ristocetin was in the low normal range, and aggregation with thrombin was normal. While desmopressin completely normalized R.H.'s bleeding time, none of these platelet parameters were improved. No differences in the SDS PAGE protein patterns of RH platelets could be detected in comparison to normal samples. His platelets took up and released serotonin (5HT) normally, and electron micrographs defined no morphological abnormalities. However, no ATP was released from platelets activated with collagen, and when followed by thrombin about fourfold greater ATP was released by control platelets as compared to RH platelets. The dense granule fraction derived from RH platelets contained about 20% the level of ATP, 40% the level of ADP, and 50% the level of 5HT detected in a normal sample. The results indicate that the bleeding disorder is related to a non-classical heritable storage pool defect. The connection between the inherited sideroblastic anemia and platelet defects is obscure.

  13. Reaction rate estimation of controlled-release antifouling paint binders: Rosin-based systems

    DEFF Research Database (Denmark)

    Meseguer Yebra, Diego; Kiil, Søren; Dam-Johansen, Kim

    2005-01-01

    at product optimisation and innovation (e.g. incorporation of natural active agents). This study seeks to attain scientifically founded knowledge of the reaction mechanisms and the rate of reaction with sea water of a Zn-carboxylate of a synthetic rosin compound. The kinetic expression attained can be used...... have shown that mathematical coating models based on a fundamental knowledge of the underlying mechanisms of A/F paints is a promising tool for accelerated product testing at different operational conditions of a sailing ship or a paint rotor. Such models can also be used for generation of ideas aiming...... rather than pointing at a certain diffusion control in the reaction rate experiments. The reverse reaction is found not to affect the hydrolysis rate within the pores, of antifouling paints significantly. It is concluded, from the reaction mechanism proposed, that the observed partial exchange of Zn2...

  14. Biochemical and functional abnormalities in hypercholesterolemic rabbit platelets

    Energy Technology Data Exchange (ETDEWEB)

    Dalal, K.B.; Ebbe, S.; Mazoyer, E.; Carpenter, D.; Yee, T. (Lawrence Berkeley Laboratory, CA (USA))

    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.

  15. NOSH-sulindac (AVT-18A) is a novel nitric oxide- and hydrogen sulfide-releasing hybrid that is gastrointestinal safe and has potent anti-inflammatory, analgesic, antipyretic, anti-platelet, and anti-cancer properties.

    Science.gov (United States)

    Kashfi, Khosrow; Chattopadhyay, Mitali; Kodela, Ravinder

    2015-12-01

    Sulindac is chemopreventive and has utility in patients with familial adenomatous polyposis; however, side effects preclude its long-term use. NOSH-sulindac (AVT-18A) releases nitric oxide and hydrogen sulfide, was designed to be a safer alternative. Here we compare the gastrointestinal safety, anti-inflammatory, analgesic, anti-pyretic, anti-platelet, and anti-cancer properties of sulindac and NOSH-sulindac administered orally to rats at equimolar doses. Gastrointestinal safety: 6h post-administration, number/size of hemorrhagic lesions in stomachs were counted. Tissue samples were frozen for PGE2, SOD, and MDA determination. Anti-inflammatory: 1h after drug administration, the volume of carrageenan-induced rat paw edemas was measured for 5h. Anti-pyretic: fever was induced by LPS (ip) an hour before administration of the test drugs, core body temperature was measured hourly for 5h. Analgesic: time-dependent analgesic effects were evaluated by carrageenan-induced hyperalgesia. Antiplatelet: anti-aggregatory effects were studied on collagen-induced platelet aggregation of human platelet-rich plasma. Anti-cancer: We examined the effects of NOSH-sulindac on the growth properties of 12 human cancer cell lines of six different tissue origins. Both agents reduced PGE2 levels in stomach tissue; however, NOSH-sulindac did not cause any stomach ulcers, whereas sulindac caused significant bleeding. Lipid peroxidation induced by sulindac was higher than that from NOSH-sulindac. SOD activity was significantly lowered by sulindac but increased by NOSH-sulindac. Both agents showed similar anti-inflammatory, analgesic, anti-pyretic, and anti-platelet activities. Sulindac increased plasma TNFα whereas this rise was lower in the NOSH-sulindac-treated animals. NOSH-sulindac inhibited the growth of all cancer cell lines studied, with potencies of 1000- to 9000-fold greater than that of sulindac. NOSH-sulindac inhibited cell proliferation, induced apoptosis, and caused G2/M cell

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

    Science.gov (United States)

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

    2016-03-01

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

  17. Platelet inhibition by nitrite is dependent on erythrocytes and deoxygenation.

    Directory of Open Access Journals (Sweden)

    Sirada Srihirun

    Full Text Available 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.

  18. Proton transfer reaction mass spectrometry and time intensity perceptual measurement of flavor release from lipid emulsions using trained human subjects.

    Science.gov (United States)

    Frank, Damian; Appelqvist, Ingrid; Piyasiri, Udayasika; Wooster, Tim J; Delahunty, Conor

    2011-05-11

    The effect of the fat component of liquid emulsions on dynamic "in-nose" flavor release was examined using a panel of trained human subjects (n = 6), proton transfer reaction mass spectrometry (PTR-MS), and time intensity (TI) sensory evaluation. A rigorous breathing and consumption protocol was developed, which synchronized subjects' breathing cycles and also the timing of sample introduction. Temporal changes in volatile release were measured in exhaled nostril breath by real-time PTR-MS. Corresponding changes in the perceived odor intensity could also be simultaneously measured using a push button TI device. The method facilitated accurate examination of both "preswallow" and "postswallow" phases of volatile release and perception. Volatile flavor compounds spanning a range of octanol/water partition coefficient (K(o/w)) values (1-1380) were spiked into water (0% fat) or lipid emulsions with various fat contents (2, 5, 10, and 20% fat). Replicate samples for each fat level were consumed according to the consumption protocol by six subjects. Statistical comparisons were made at the individual level and across the group for the effects of changes in the food matrix, such as fat content, on both pre- and postswallow volatile release. Significant group differences in volatile release parameters including area under the concentration curve (AUC) and maximum concentration (I(max)) were measured according to the lipid content of emulsions and volatile K(o/w). In a second experiment, using single compounds (2-heptanone, ethyl butanoate, and ethyl hexanoate), significant decreases in both in-nose volatile release and corresponding perceived odor intensities were measured with increasing fat addition. Overall, the effect of fat on in vivo release conformed to theory; fat had little effect on compounds with low K(o/w) values, but increased for volatiles with higher lipophilicity. In addition, significant pre- and postswallow differences were observed in AUC and I(max), as

  19. Platelet Function Tests

    Science.gov (United States)

    ... be limited. Home Visit Global Sites Search Help? Platelet Function Tests Share this page: Was this page helpful? ... their patients by ordering one or more platelet function tests. Platelet function testing may include one or more of ...

  20. Congenital platelet function defects

    Science.gov (United States)

    ... storage pool disorder; Glanzmann's thrombasthenia; Bernard-Soulier syndrome; Platelet function defects - congenital ... Congenital platelet function defects are bleeding disorders that ... function, even though there are normal platelet numbers. Most ...

  1. Unaltered Angiogenesis-Regulating Activities of Platelets in Mild Type 2 Diabetes Mellitus despite a Marked Platelet Hyperreactivity

    Science.gov (United States)

    Miao, Xinyan; Zhang, Wei; Huang, Zhangsen

    2016-01-01

    Type 2 diabetes mellitus (T2DM) is associated with platelet dysfunction and impaired angiogenesis. Aim of the study is to investigate if platelet dysfunction might hamper platelet angiogenic activities in T2DM patients. Sixteen T2DM patients and gender/age-matched non-diabetic controls were studied. Flow cytometry and endothelial colony forming cell (ECFC) tube formation on matrigel were used to assess platelet reactivity and angiogenic activity, respectively. Thrombin receptor PAR1-activating peptide (PAR1-AP) induced higher platelet P-selectin expression, and evoked more rapid and intense platelet annexin V binding in T2DM patients, seen as a more rapid increase of annexin V+ platelets (24.3±6.4% vs 12.6±3.8% in control at 2 min) and a higher elevation (30.9±5.1% vs 24.3±3.0% at 8 min). However, PAR1-AP and PAR4-AP induced similar releases of angiogenic regulators from platelets, and both stimuli evoked platelet release of platelet angiogenic regulators to similar extents in T2DM and control subjects. Thus, PAR1-stimulated platelet releasate (PAR1-PR) and PAR4-PR similarly enhanced capillary-like network/tube formation of ECFCs, and the enhancements did not differ between T2DM and control subjects. Direct supplementation of platelets to ECFCs at the ratio of 1:200 enhanced ECFC tube formation even more markedly, leading to approximately 100% increases of the total branch points of ECFC tube formation, for which the enhancements were also similar between patients and controls. In conclusion, platelets from T2DM subjects are hyperreactive. Platelet activation induced by high doses of PAR1-AP, however, results in similar releases of angiogenic regulators in mild T2DM and control subjects. Platelets from T2DM and control subjects also demonstrate similar enhancements on ECFC angiogenic activities. PMID:27612088

  2. In-vitro release pharmacokinetics of amikacin, teicoplanin and polyhexanide in a platelet rich fibrin—layer (PRF)—a laboratory evaluation of a modern, autologous wound treatment

    Science.gov (United States)

    Thalhammer, Florian

    2017-01-01

    Objectives Platelet rich fibrin (PRF) is an autologous fibrin glue, produced from patients' blood, which, besides intraoperative use, has applications in the treatment of infected wounds. The combination with antimicrobial agents results in a prolonged antibacterial effect allowing for wound dressing change intervals of seven days even in infected wounds. The aim of this study was to evaluate release kinetics of amikacin, teicoplanin or polyhexanide from a PRF-layer. Methods PRF mixed with teicoplanin, amikacin or polyhexanide was sprayed on a silicon gauze patch and put on a colombia agar with bacteria with known minimal inhibitory concentration (MIC) and incubated for 24 hours and afterwards transferred to another agar with the same bacterial strain. Inhibition zones were measured every 24 hours. This was repeated on 7 consecutive days. Antibiotic concentrations were calculated by interpolation. Results More than 1000 mg/L teicoplanin were released within the first 24 hours and 28.22 mg/L after 168 hours. Amikacin release was above 10,000 mg/L within the first 24 hours and still 120.8 mg/L after 120 hours. A release of polyhexanide could be verified for the first 24 hours only. Consequently teicoplanin and amikacin released from PRF showed antimicrobial in-vitro effects for almost a week, whereas an antimicrobial effect of polyhexanide could only be verified for the first 24 hours. Conclusions Our Results show that a weekly dressing regimen may be justified in wounds treated with PRF plus amikacin or teicoplanin, since bacteria will be eradicated over a considerable period of time after a single application of PRF. PMID:28686663

  3. Inhibition of a solid phase reaction among excipients that accelerates drug release from a solid dispersion with aging.

    Science.gov (United States)

    Mizuno, Masayasu; Hirakura, Yutaka; Yamane, Ikuro; Miyanishi, Hideo; Yokota, Shoji; Hattori, Munetaka; Kajiyama, Atsushi

    2005-11-23

    Hydrophobic drug substances can be formulated as a solid dispersion or solution using macromolecular matrices with high glass transition temperatures to attain satisfactory dissolution. However, very few marketed products have previously relied on solid dispersion technology due to physical and chemical instability problems, and processing difficulties. In the present study, a modified release product of a therapeutic drug for hypertension, Barnidipine hydrochloride, was developed. The drug product consisted of solid dispersion based on a matrix of carboxymethylethylcellulose (CMEC), which was produced using the spray-coating method. An enteric coat layer was sprayed on the surface of the solid dispersion to control drug release. Interestingly, the release rate accelerated as the drug product aged, while there were no indications of deceleration of the release rate which was due to crystallization of the drug substance. To prevent changes in the dissolution kinetics during storage periods, a variety of processing conditions were tried. It was found that not only use of non-aqueous solvents but also a reduction in coating temperatures consistently resulted in stable solid dispersions. The molecular bases of dissolution of the drug substance from those matrices were investigated. The molecular weight of CMEC was found to be a dominant factor that determined dissolution kinetics, which followed zero-order release, suggesting an involvement of an osmotic pumping mechanism. While dissolution was faster using a higher molecular weight CMEC, the molecular weight of CMEC in the drug product slowly increased with aging (solid phase reaction) depending on the processing conditions, causing the time-induced elevation of dissolution. While no crystalline components were found in the solid dispersion, the amorphous structure maintained a degree of non-equilibrium by nature. Plasticization by water in the coating solution relaxed the amorphous system and facilitated phase

  4. [Platelet allo-antibodies identification strategies for preventing and managing platelet refractoriness].

    Science.gov (United States)

    Basire, A; Picard, C

    2014-11-01

    Platelet refractoriness is a serious complication for patients receiving recurrent platelet transfusions, which can be explained by non-immune and immune causes. Human Leukocyte Antigens (HLA) allo-immunization, especially against HLA class I, is the major cause for immune platelet refractoriness. To a lesser extent, allo-antibodies against specific Human Platelet Antigen (HPA) are also involved. Pregnancy, transplantation and previous transfusions can lead to allo-immune reaction against platelet antigens. After transfusion, platelet count is decreased by accelerated platelet destruction related to antibodies fixation on incompatible platelet antigens. New laboratory tests for allo-antibodies identification were developed to improve sensibility and specificity, especially with the LUMINEX(®) technology. The good use and interpretation of these antibodies assays can improve strategies for platelet refractoriness prevention and management with a patient adapted response. Compatible platelets units can be selected according to their identity with recipient typing or immune compatibility regarding HLA or HPA antibodies or HLA epitope compatibility. Prospective studies are needed to further confirm the clinical benefit of new allo-antibodies identification methods and consensus strategies for immune platelet refractoriness management.

  5. The release of stored energy in heavily irradiated NaCl explosive reactions

    NARCIS (Netherlands)

    Vainshtein, D.; Bemt, M. van den; Seinen, J.; Datema, H.C.; Hartog, H.W. den

    1995-01-01

    During irradiation of NaCl with ionizing radiation at moderate temperatures (50-150 degrees C) irregular structures of very fine Na and Cl nano-precipitates are formed. The increase of the temperature to a value between 50 and 250 degrees C might induce explosive reactions between radiolytic Na and

  6. [Stereological analysis of the degranulation and the contraction of platelets. Application to the ultrastructural study of thrombin induced excretion in vitro].

    Science.gov (United States)

    Bryon, P A; Lagarde, M; Dechavanne, M

    1975-12-01

    A stereological model, which provides quantitative information on the morphology of the platelet release reaction as isolated from platelet aggregation, was developed for the human platelets separated from blood by Mustard's procedure. Three morphologically defined spaces (granules, surface-connected canalicular system S.C.S., cytoplasm) were used to characterize platelet degranulation (with the variation of the volume density of the granules) and contraction (with the variation of the volume density of both granules and S.C.S.). This model was applied to the evaluation of ultrastructural changes associated with the thrombin-induced release reaction. Degranulation and contraction were associated in the platelets which had been allowed to release for 1,5 and 150 sec. Under conditions of the study, prostaglandins E1 (10(-7) M) inhibited both degranulation and contraction (p less than 0,001). Aspirin (10(-4) M) only inhibited contraction (p less than 0.01) and dibutyryl-AMPc (10(-4)) only inhibited granulation (p less than 0,001).

  7. Hanford Tank 241-C-106: Impact of Cement Reactions on Release of Contaminants from Residual Waste

    Energy Technology Data Exchange (ETDEWEB)

    Deutsch, William J.; Krupka, Kenneth M.; Lindberg, Michael J.; Cantrell, Kirk J.; Brown, Christopher F.; Schaef, Herbert T.

    2006-09-01

    The CH2M HILL Hanford Group, Inc. (CH2M HILL) is producing risk/performance assessments to support the closure of single-shell tanks at the U.S. Department of Energy's Hanford Site. As part of this effort, staff at Pacific Northwest National Laboratory were asked to develop release models for contaminants of concern that are present in residual sludge remaining in tank 241-C-106 (C-106) after final retrieval of waste from the tank. Initial work to produce release models was conducted on residual tank sludge using pure water as the leaching agent. The results were reported in an earlier report. The decision has now been made to close the tanks after waste retrieval with a cementitious grout to minimize infiltration and maintain the physical integrity of the tanks. This report describes testing of the residual waste with a leaching solution that simulates the composition of water passing through the grout and contacting the residual waste at the bottom of the tank.

  8. Platelets as immune mediators: Their role in host defense responses and sepsis

    OpenAIRE

    Li, Zhenyu; Yang, Fanmuyi; Dunn, Steve; Gross, A. Kendall; Smyth, Susan S.

    2010-01-01

    Platelets occupy a central role at the interface between thrombosis and inflammation. At sites of vascular damage, adherent platelets physically and functionally interact with circulating leukocytes. Activated platelets release soluble factors into circulation that may have local and systemic effects on blood and vascular cells. Platelets can also interact with a wide variety of microbial pathogens. Emerging evidence from animal models suggests that platelets may participate in a wide variety...

  9. Study on Membrane Microstructures and Characteristics of Infrared Spectra and Nitrogen Release of Solid-Liquid Reaction Coated Urea

    Institute of Scientific and Technical Information of China (English)

    MAO Xiao-yun; FENG Xin; WANG De-han; SUN Ke-jun; LIAO Zong-wen

    2004-01-01

    The membrane microstructures and the mechanism of two coated ureas formed through solidliquid reaction were observed by scanning electron microscope and infrared spectra, the relation of the structural characteristics with the nitrogen release feature was also discussed by combining with nitrogen dissolution in water. The results showed that the membranes were made of solid particles tightly connected to each other and were piled up layer by layer through liquid glue. Porosity and aperture of membrane were determined by compactness of piled layers and the particles in a single layer and also related to the characteristics of coating materials. Research of the infrared spectra of membrane, made of a solid powder and a liquid glue, proved that O-H on the solid surface was bonded with the double bond of the liquid glue, thus forming membrane and keeping it stable. It was found that the two coated ureas showed obvious differences in nitrogen releasing due to their membrane structures, the porosity and aperture of membrane were the critical factors for nitrogen releasing.

  10. Platelet concentrates, from whole blood or collected by apheresis?

    Science.gov (United States)

    van der Meer, Pieter F

    2013-04-01

    Platelet concentrates can be isolated from donated whole blood with the platelet-rich plasma-method or the buffy coat-method. Alternatively, platelets can be obtained by apheresis, harvesting the platelets but returning all other cells to the donor. The quality and characteristics of platelets during storage are affected by a number of factors, such as anticoagulant, centrifugation and processing after collection, and pre- or post storage pooling, but when comparing literature on the various methods, most differences balance out. To have sufficient platelets to treat an adult patient, whole-blood-derived platelet concentrates need pooling of multiple donations, thereby increasing the risk of infectious agent transmission at least two-fold as compared with apheresis units. Allo immunization rates, acute reaction rates, and transfusion related acute lung injury rates are not different. Apheresis donation procedures have fewer adverse events. All these factors need to be considered and weighed when selecting a method of platelet collection for a blood center.

  11. Migration inhibitory factor (MIF) released by macrophages upon recognition of immune complexes is critical to inflammation in Arthus reaction.

    Science.gov (United States)

    Paiva, Claudia N; Arras, Rosa H; Magalhães, Elisabeth S; Alves, Letícia S; Lessa, Luiz Paulo; Silva, Maria Helena; Ejzemberg, Regina; Canetti, Cláudio; Bozza, Marcelo T

    2009-05-01

    Deposition of immune complexes (IC) triggers Fc gamma R-dependent inflammation, leading to tissue damage in rheumatoid arthritis, systemic lupus erythematous, immune glomerulonephritis, and several immune vasculitides. Evidences support a role for macrophage migration inhibitory factor (MIF) in a number of inflammatory diseases, but the triggering of its secretion and its physiopathological role upon IC deposition remain elusive. Herein, we show that human macrophages secreted MIF after IC recognition, which in turn controlled the secretion of TNF. Macrophages from Mif-/- mice produced smaller amounts of TNF when stimulated with IgG-opsonized erythrocytes than wild-type (WT) cells. Using passive reverse Arthus reaction in the peritoneum and lungs as a model for IC-induced inflammation, we demonstrated that Mif-/- mice had a milder response, observed by reduced neutrophil recruitment, vascular leakage, and secretion of TNF, MIP-2, and keratinocyte-derived chemokine compared with WT controls. Adoptive transfer of alveolar macrophages from WT to Mif-/- mice rescued pulmonary neutrophil recruitment and TNF production upon passive reverse Arthus reaction. Our study indicates that Arthus inflammatory reaction is largely dependent on MIF and poses macrophages as a source of the MIF released upon IC recognition. These results give experimental support to the proposition that blockade of MIF might constitute an adjunctive, therapeutic approach to IC disease.

  12. Three-dimensional Printed Scaffolds with Gelatin and Platelets Enhance In vitro Preosteoblast Growth Behavior and the Sustained-release Effect of Growth Factors

    Directory of Open Access Journals (Sweden)

    Wei Zhu

    2016-01-01

    Conclusions: Our experiments confirmed that the 3D printed scaffolds we had designed could provide a sustained-release effect for growth factors and improve the proliferation of preosteoblasts with little cytotoxicity in vitro. They may hold promise as bone graft substitute materials in the future.

  13. Platelet-derived Growth-factor-releasing Aligned Collagen-nanoparticle Fibers Promote the Proliferation and Tenogenic Differentiation of Adipose-derived Stem Cells

    Science.gov (United States)

    2013-11-27

    and tested to determine their tensile mechanical properties. Both ends of dried bundles were fixed between thin PVC tabs using cyanoacrylate, and the...1–10. [25] Wei GB, Jin QM, Giannobile WV, Ma PX. Nano -fibrous scaffold for controlled delivery of recombinant human PDGF-BB. J Control Release

  14. Platelet matching for alloimmunized patients

    Institute of Scientific and Technical Information of China (English)

    S H.Hsu

    2010-01-01

    @@ Platelets play an essential role in blood coagulation,hemostasis and maintenance of vascular integrity.Platelets are utilized primarily to prevent or treat bleeding in thrombocytopenic patients and patients with impaired platelet production in the bone marrow and/or with dysfunctional platelets.In current practice,platelet transfusion begins with randomly selected platelet products:either pooled platelets prepared from whole blood derived platelets; or single donor platelets prepared by apheresis procedures.

  15. Platelets as immune cells in infectious diseases.

    Science.gov (United States)

    Speth, Cornelia; Löffler, Jürgen; Krappmann, Sven; Lass-Flörl, Cornelia; Rambach, Günter

    2013-11-01

    Platelets have been shown to cover a broad range of functions. Besides their role in hemostasis, they have immunological functions and thus participate in the interaction between pathogens and host defense. Platelets have a broad repertoire of receptor molecules that enable them to sense invading pathogens and infection-induced inflammation. Consequently, platelets exert antimicrobial effector mechanisms, but also initiate an intense crosstalk with other arms of the innate and adaptive immunity, including neutrophils, monocytes/macrophages, dendritic cells, B cells and T cells. There is a fragile balance between beneficial antimicrobial effects and detrimental reactions that contribute to the pathogenesis, and many pathogens have developed mechanisms to influence these two outcomes. This review aims to highlight aspects of the interaction strategies between platelets and pathogenic bacteria, viruses, fungi and parasites, in addition to the subsequent networking between platelets and other immune cells, and the relevance of these processes for the pathogenesis of infections.

  16. Assessment of the influence of the inflammatory process on the activation of blood platelets and morphological parameters in patients with ulcerative colitis (colitis ulcerosa

    Directory of Open Access Journals (Sweden)

    Beata Polińska

    2011-04-01

    Full Text Available Ulcerative colitis (colitis ulcerosa is a non-specific inflammatory bowel disease of unknown etiology. Thesymptoms which are observed in the course of ulcerative colitis are: an increase in the number of leukocytes andblood platelets, an increase in the concentration of IL-6 and anemia. Blood platelets are the key element, linkingthe processes of hemostasis, inflammation and the repair of damaged tissues. Activation of blood platelets is connectedwith changes in their shape and the occurrence of the reaction of release. P-selectin appears on the surfacesof activated blood platelets and the concentration level of soluble P-selectin increases in the blood plasma. The aimof this study was to define whether the increased number of blood platelets in patients with ulcerative colitisaccompanies changes in their activation and morphology. A total of 16 subjects with ulcerative colitis and 32healthy subjects were studied. Mean platelet count, morphological parameters of platelets and MPC were measuredusing an ADVIA 120 hematology analyzer. Concentrations of sP-selectin and IL-6 in serum were marked byimmunoassay (ELISA. MPC, concentration of sP-selectin and IL-6 were significantly higher in subjects with ulcerativecolitis compared to those in the healthy group. There was a decrease of MPV in patients with ulcerativecolitis, which is statistically significant. Chronic inflammation in patients with ulcerative colitis causes an increase inthe number of blood platelets, a change in their morphology and activation. Decreased MPV value reflects activationand the role blood platelets play in the inflammatory process of the mucous membrane of the colon. A highconcentration of sP-selectin, which is a marker of blood platelet activation, demonstrates their part in the inflammatoryprocess. The increase in the concentration of sP-selectin correlated positively with the increase in concentrationof IL-6. This is why it may be a useful marker of the activity of

  17. [The role of blood platelets in infections].

    Science.gov (United States)

    Micota, Bartłomiej; Sadowska, Beata; Różalska, Barbara

    2015-05-17

    Platelets are primarily associated with their main function, hemostasis, although it is known that these cells also exhibit biological activity in cancer progression, inflammation and infectious processes. During infection platelets, due to the expression of specific receptors - Toll-like receptors (TLRs) - which recognize molecular patterns associated with pathogens - pathogen-associated molecular patterns (PAMPs) - are activated by the presence of microorganism components and/or substances released from damaged cells/tissue. Further antimicrobial activity of platelets is based on their capacity for phagocytosis, generation of reactive oxygen species (ROS), and the synthesis, storage and release of proteins/peptides with antimicrobial activity. Another mechanism of platelet action is their immunomodulatory activity. It is based mainly on the ability to secrete chemotactic factors allowing the accumulation of professional immunocompetent cells at the site of infection, thus enhancing the effective eradication of an infectious agent. In chronic infections, platelets, due to release of numerous growth factors and various cytokines, support mechanisms of acquired immunity. They accelerate the maturation of dendritic cells, stimulate B cells to be immunoglobulin-producing plasma cells and potentiate the activity of T cells. Unfortunately, in certain situations (the existence of specific risk factors) the interaction of microorganisms with activated platelets may also be the cause of pathology within the cardiovascular system.

  18. Release the BEESTS: Bayesian Estimation of Ex-Gaussian STop-Signal Reaction Time Distributions

    Directory of Open Access Journals (Sweden)

    Dora eMatzke

    2013-12-01

    Full Text Available The stop-signal paradigm is frequently used to study response inhibition. Inthis paradigm, participants perform a two-choice response time task wherethe primary task is occasionally interrupted by a stop-signal that promptsparticipants to withhold their response. The primary goal is to estimatethe latency of the unobservable stop response (stop signal reaction timeor SSRT. Recently, Matzke, Dolan, Logan, Brown, and Wagenmakers (inpress have developed a Bayesian parametric approach that allows for theestimation of the entire distribution of SSRTs. The Bayesian parametricapproach assumes that SSRTs are ex-Gaussian distributed and uses Markovchain Monte Carlo sampling to estimate the parameters of the SSRT distri-bution. Here we present an efficient and user-friendly software implementa-tion of the Bayesian parametric approach —BEESTS— that can be appliedto individual as well as hierarchical stop-signal data. BEESTS comes withan easy-to-use graphical user interface and provides users with summarystatistics of the posterior distribution of the parameters as well various diag-nostic tools to assess the quality of the parameter estimates. The softwareis open source and runs on Windows and OS X operating systems. In sum,BEESTS allows experimental and clinical psychologists to estimate entiredistributions of SSRTs and hence facilitates the more rigorous analysis ofstop-signal data.

  19. Reaction kinetics and validity of BOD test for domestic wastewater released in marine ecosystems.

    Science.gov (United States)

    Dhage, Shivani S; Dalvi, Amita A; Prabhu, Damodar V

    2012-09-01

    With urbanization of coastal cities, marine pollution is becoming a severe problem. The rates of biodegradation, decomposition, and ratification of pollutants get slowed down due to salinity. The higher temperatures prevalent in tropical regions significantly affect reaction rates. Multiple factors influence the rate of biodegradation, making the process complex. Hence, prediction and evaluation of the assimilative capacity of the marine environment due to wastewater discharges is becoming a difficult task. Biochemical oxygen demand (BOD) is a wet oxidation process, which follows first-order kinetics. The values of kinetic rate constants are expected to differ with varying salinities and temperatures. Research is carried out using glucose-glutamic acid and domestic wastewater to evaluate the impact of salinity on biodegradation of carbonaceous waste at 20°C and 27°C. The findings confirm the hypothesis of slow biodegradation of carbonaceous organic matter in marine waters. An inverse relationship between rate of biodegradation and salinity was observed. BOD exertion at 20°C (5 days) and 27°C (3 days) for the marine environment is comparable at selected salinities thereby confirming the validity of BOD test of shorter duration at elevated temperature.

  20. Thrombopoietin induces p-selectin expression on platelets and subsequent platelet/leukocyte interactions.

    Science.gov (United States)

    Tibbles, Heather E; Navara, Christopher S; Hupke, Michael A; Vassilev, Alexei O; Uckun, Fatih M

    2002-04-12

    Ligation of thrombopoietin (TPO) to the platelet c-Mpl receptor induces numerous biochemical pathways in the absence of aggregation. Two forms of recombinant TPO are currently in clinical trials for the treatment of thrombocytopenia. This study focuses on the effects of the full-length recombinant human TPO (rhTPO) on platelets in a whole blood system. Platelet-leukocyte associations (PLAs) were visualized following rhTPO stimulation as CD42b/CD 45 double positive clusters by FACS analysis. Treatment of washed platelets with rhTPO induced granule release and expression of the leukocyte adhesion receptor P-selectin (CD 62P) in the absence of aggregation and calcium mobilization. RhTPO also induced platelet-leukocyte interactions in whole blood. Following stimulation, leukocytes were recruited by platelets through P-selectin in a calcium-dependent manner. rhTPO stimulates platelet-leukocyte associations in whole blood through expression of platelet P-selectin. To our knowledge, this is the first report that identifies TPO as a promoter of platelet-leukocyte interactions.

  1. Understanding platelet generation from megakaryocytes: implications for in vitro-derived platelets.

    Science.gov (United States)

    Sim, Xiuli; Poncz, Mortimer; Gadue, Paul; French, Deborah L

    2016-03-10

    Platelets are anucleate cytoplasmic discs derived from megakaryocytes that circulate in the blood and have major roles in hemostasis, thrombosis, inflammation, and vascular biology. Platelet transfusions are required to prevent the potentially life-threatening complications of severe thrombocytopenia seen in a variety of medical settings including cancer therapy, trauma, and sepsis. Platelets used in the clinic are currently donor-derived which is associated with concerns over sufficient availability, quality, and complications due to immunologic and/or infectious issues. To overcome our dependence on donor-derived platelets for transfusion, efforts have been made to generate in vitro-based platelets. Work in this area has advanced our understanding of the complex processes that megakaryocytes must undergo to generate platelets both in vivo and in vitro. This knowledge has also defined the challenges that must be overcome to bring in vitro-based platelet manufacturing to a clinical reality. This review will focus on our understanding of committed megakaryocytes and platelet release in vivo and in vitro, and how this knowledge can guide the development of in vitro-derived platelets for clinical application.

  2. Growth Factor Variation in Two Types of Autologous Platelet Biomaterials: PRP Versus PRF.

    Science.gov (United States)

    Arora, Satyam; Kotwal, Urvershi; Dogra, Mitu; Doda, Veena

    2017-06-01

    Autologous platelet biomaterials represent a key source of cytokines and growth factors extensively used for clinical and surgical applications involving tissue regeneration; wound healing and tissue repair. In this communication we discuss the growth factors released by activated platelet rich plasma (PRP) and platelet rich fibrin (PRF) releasate. Our study highlights that significantly higher growth factors (TGF-ß1) are released by activated PRP as compared to releasate of PRF. The various growth factors released by both platelet products are significantly higher than the baseline concentration in the whole blood and have different bio-mechanism hence should be individualized as per the clinical indication.

  3. Effect of safflower yellow on platelet activating factor mediated platelet activation in patients with coronary heart disease

    Directory of Open Access Journals (Sweden)

    Damin Huang

    2012-06-01

    Full Text Available The platelet aggregation and 5-HT release by washed platelet from coronary heart disease patients following platelet activating factor (PAF treatment were detected by turbidimetry and O-phthalaldehyde assay. The free calcium concentration in the platelets was measured with the fura-2/AM probe fluorescent technique. Results showed safflower yellow could inhibit the PAF induced washed platelet aggregation and 5-HT release, which were in a safflor-yellow-dose dependent manner. When the PAF was 2.0×10-9 mol/L, the inhibition rate of platelet aggregation was 26.2%, 41.3%, 58.1%, 81.2%, and the inhibition rate of 5-HT release was 3.7%, 11.9%, 29.9% and 54.4% after treatment with safflower yellow at 0.21, 0.42, 0.85 and 1.69 g/L, respectively. The study concludes safflower yellow can inhibit the PAF induced platelet aggregation, 5-HT release by platelets and elevation of free calcium in platelets.

  4. Exercise-induced changes in the in vivo distribution of /sup 111/In-labelled platelets

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, K.G.; Waever Rasmussen, J. (Department of Radiophysics, Odense University Hospital, Odense, Denmark)

    1984-01-01

    In order to throw some light on the mechanisms underlying exercise-induced thrombocytosis, we investigated 15 healthy persons subjected to short-term vigorous pedalling on a bicycle ergometer 1 d after injection of autologous /sup 111/In-labelled platelets. Scintigraphic studies during the post-excercise period showed the spleen to be the major platelet-releasing organ. There was, however, a considerable interindividual variability manifested as signs of a contributing platelet release from the lungs in some cases and of deposition of a surplus of released platelets in the liver of others. Our results also seem to be compatible with the existence of an intravascular marginal platelet pool.

  5. Gut Microbial Metabolite TMAO Enhances Platelet Hyperreactivity and Thrombosis Risk.

    Science.gov (United States)

    Zhu, Weifei; Gregory, Jill C; Org, Elin; Buffa, Jennifer A; Gupta, Nilaksh; Wang, Zeneng; Li, Lin; Fu, Xiaoming; Wu, Yuping; Mehrabian, Margarete; Sartor, R Balfour; McIntyre, Thomas M; Silverstein, Roy L; Tang, W H Wilson; DiDonato, Joseph A; Brown, J Mark; Lusis, Aldons J; Hazen, Stanley L

    2016-03-24

    Normal platelet function is critical to blood hemostasis and maintenance of a closed circulatory system. Heightened platelet reactivity, however, is associated with cardiometabolic diseases and enhanced potential for thrombotic events. We now show gut microbes, through generation of trimethylamine N-oxide (TMAO), directly contribute to platelet hyperreactivity and enhanced thrombosis potential. Plasma TMAO levels in subjects (n > 4,000) independently predicted incident (3 years) thrombosis (heart attack, stroke) risk. Direct exposure of platelets to TMAO enhanced sub-maximal stimulus-dependent platelet activation from multiple agonists through augmented Ca(2+) release from intracellular stores. Animal model studies employing dietary choline or TMAO, germ-free mice, and microbial transplantation collectively confirm a role for gut microbiota and TMAO in modulating platelet hyperresponsiveness and thrombosis potential and identify microbial taxa associated with plasma TMAO and thrombosis potential. Collectively, the present results reveal a previously unrecognized mechanistic link between specific dietary nutrients, gut microbes, platelet function, and thrombosis risk.

  6. Platelet affinity for burro aorta collagen

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, M.D.

    1977-10-01

    Despite ingenious concepts, there are no unequivocal clues as to what, when, and how some undefined biochemical factor(s) or constituent(s) that localizes in the arterial wall can precipitate a thromboatheromatous lesion or arterial disease. The present study focused on the extraction, partial purification, and characterization of a collagen-active platelet stimulator from the aortas of aged burros. The aggregator moiety in the aorta extracts invariably had a higher affinity for platelets in citrated platelet-rich plasma of human beings than for platelets of homologous burros. The platelet-aggregating factor(s) in the aorta extract was retained by incubation with ..cap alpha..-chymotrypsin. Platelet-aggregating activity was rapidly abolished after incubation with collagenase, as determined by platelet-aggregometry tests. Evidence based on light microscope and polysaccharide histochemical reactions indicates a probability that the intracellular amorphous matrix (PAS-positive) and filamentous components (PTAH-positive) expelled from smooth muscle cells disrupted during homogenization of the aorta may be a principal source of a precursor collagen species which is a potent inducer of platelet aggregation.

  7. Platelet Content of Nitric Oxide Synthase 3 Phosphorylated At Serine1177 Is Associated with the Functional Response of Platelets to Aspirin

    Science.gov (United States)

    Modrego, Javier; Azcona, Luis; Martín-Palacios, Naiara; Zamorano-León, José J.; Segura, Antonio; Rodríguez, Pablo; Guerra, Reddy; Tamargo, Juan; Macaya, Carlos; López-Farré, Antonio J.

    2013-01-01

    Objective To analyse if platelet responsiveness to aspirin (ASA) may be associated with a different ability of platelets to generate nitric oxide (NO). Patients/Methods Platelets were obtained from 50 patients with stable coronary ischemia and were divided into ASA-sensitive (n = 26) and ASA-resistant (n = 24) using a platelet functionality test (PFA-100). Results ASA-sensitive platelets tended to release more NO (determined as nitrite + nitrate) than ASA-resistant platelets but it did not reach statistical significance. Protein expression of nitric oxide synthase 3 (NOS3) was higher in ASA-sensitive than in ASA-resistant platelets but there were no differences in the platelet expression of nitric oxide synthase 2 (NOS2) isoform. The highest NOS3 expression in ASA-sensitive platelets was independent of the presence of T-to-C mutation at nucleotide position −786 (T−786→C) in the NOS3-coding gene. However, platelet content of phosphorylated NOS3 at Serine (Ser)1177, an active form of NOS3, was higher in ASA-sensitive than in ASA-resistant platelets. The level of platelet NOS3 Ser1177 phosphorylation was positively associated with the closure time in the PFA-100 test. In vitro, collagen failed to stimulate the aggregation of ASA-sensitive platelets, determined by lumiaggregometry, and it was associated with a significant increase (p = 0.018) of NOS3 phosphorylation at Ser1177. On the contrary, collagen stimulated the aggregation of ASA-resistant platelets but did not significantly modify the platelet content of phosphorylated NOS3 Ser1177. During collagen stimulation the release of NO from ASA-sensitive platelets was significantly enhanced but it was not modified in ASA-resistant platelets. Conclusions Functional platelet responsiveness to ASA was associated with the platelet content of phosphorylated NOS3 at Ser1177. PMID:24376548

  8. Platelet content of nitric oxide synthase 3 phosphorylated at Serine 1177 is associated with the functional response of platelets to aspirin.

    Directory of Open Access Journals (Sweden)

    Javier Modrego

    Full Text Available OBJECTIVE: To analyse if platelet responsiveness to aspirin (ASA may be associated with a different ability of platelets to generate nitric oxide (NO. PATIENTS/METHODS: Platelets were obtained from 50 patients with stable coronary ischemia and were divided into ASA-sensitive (n = 26 and ASA-resistant (n = 24 using a platelet functionality test (PFA-100. RESULTS: ASA-sensitive platelets tended to release more NO (determined as nitrite + nitrate than ASA-resistant platelets but it did not reach statistical significance. Protein expression of nitric oxide synthase 3 (NOS3 was higher in ASA-sensitive than in ASA-resistant platelets but there were no differences in the platelet expression of nitric oxide synthase 2 (NOS2 isoform. The highest NOS3 expression in ASA-sensitive platelets was independent of the presence of T-to-C mutation at nucleotide position -786 (T(-786 → C in the NOS3-coding gene. However, platelet content of phosphorylated NOS3 at Serine (Ser(1177, an active form of NOS3, was higher in ASA-sensitive than in ASA-resistant platelets. The level of platelet NOS3 Ser(1177 phosphorylation was positively associated with the closure time in the PFA-100 test. In vitro, collagen failed to stimulate the aggregation of ASA-sensitive platelets, determined by lumiaggregometry, and it was associated with a significant increase (p = 0.018 of NOS3 phosphorylation at Ser(1177. On the contrary, collagen stimulated the aggregation of ASA-resistant platelets but did not significantly modify the platelet content of phosphorylated NOS3 Ser(1177. During collagen stimulation the release of NO from ASA-sensitive platelets was significantly enhanced but it was not modified in ASA-resistant platelets. CONCLUSIONS: Functional platelet responsiveness to ASA was associated with the platelet content of phosphorylated NOS3 at Ser(1177.

  9. Molecular defects in the ABCA1 pathway affect platelet function.

    Science.gov (United States)

    Schmitz, Gerd; Schambeck, Christian M

    2006-01-01

    Platelet function is sensitive to alterations in cholesterol metabolism, and hypercholesterolemia is associated with enhanced platelet reagibility. Atherogenic low-density lipoproteins (LDL), in particular oxidized LDL, activate src-kinase-family-dependent signalling. In contrast, antiatherogenic high-density lipoproteins(HDL) inhibit platelet aggregation and target the phosphatidylinositol phospholipase C (PI-PLC) pathway. Sphingosine 1-phosphate is a major HDL component and may be crucial for downstream reactions of collagen-induced glycoprotein VI signalling and phosphoinositide 3-kinase. The ATP-binding cassette transporter A1 (ABCA1) regulates cell membrane phospholipid and cholesterol homeostasis and their release to lipid-poor apolipoprotein AI to generate prebeta-HDL precursor particles. ABCA1 also interacts with modulators of vesicular trafficking and number and impaired release of dense bodies from platelets. The ABCA1-NH2-terminus-associated Syntaxin-13, a SNARE complex protein, interacts with syntaxin 13-interacting protein (pallidin) whose deficiency leads to impaired platelet granule release from the dense granule Adapter Protein-3 (AP-3)-related pathway. Interestingly, the cholesterol transporter ABCG1 in addition to ABCA1 is another constituent of the AP-3 pathway, and disorders of lysosome-related organelles such as the Hermansky-Pudlack syndrome complex, Chediak-Higashi syndrome and the ceroid lipofuscinoses provide new opportunities to understand AP-3 pathway-related disorders and the irrelation to membrane phospholipid processing. ABCA1 mutations are involved in dysregulated vesicular trafficking from the trans golgi compartment to the plasma membrane, and ABCA1 R1925Q was shown to contribute to Scott syndrome, a phospholipid-processing disorder of missing surface exposure of phosphatidlyserine. The P2Y12 receptor triggers dense granule secretion by downstream effectors including the G-protein-coupled inward rectifier K+ channel-4 (GIRK-4), and

  10. Effect of thyrotropin-releasing hormone on cerebral free radical reactions following acute brain injury in rabbits

    Institute of Scientific and Technical Information of China (English)

    牛光明; 顾秀娟; 苏玉林; 万锋; 苏芳忠; 薛德麟

    2003-01-01

    Objective: To investigate the early effect of thyrotropin-releasing hormone (TRH) on cerebral free radical reactions after acute brain injury in rabbits.Methods: 30 healthy white rabbits were randomly divided into three groups: Group A (n=10), Group B (n=12) and Group C (n=8). The rabbits in Group A and Group B were injured by direct hit. At 0.5-4 hours after injury, the rabbits in Group A were injected with TRH (8 mg/kg body weight) through a vein and the rabbits in Group B were injected with normal saline of equal volume. The rabbits in Group C served as the normal control. Then all the rabbits were killed and brain tissues were obtained. The content of lipoperoxide (LPO), the activity of superoxide dismutase (SOD) and the water content of the brain tissues were measured.Results: The contents of LPO and water in brain tissues in Group A were lower and the activity of SOD was higher than those of Group B (P<0.05). After injury, intracranial pressure (ICP) rose rapidly and continuously with time passing by. When TRH was given to the animals in Group A, the rising speed of ICP slowed down significantly.Conclusions: TRH can decrease the cerebral free radical reactions and cerebral edema after acute brain injury in rats.

  11. Preanalytical requirements for flow cytometric evaluation of platelet activation: choice of anticoagulant.

    Science.gov (United States)

    Mody, M; Lazarus, A H; Semple, J W; Freedman, J

    1999-06-01

    Accurate assessment of in vivo or in vitro platelet activation requires optimal preanalytical conditions to prevent artefactual in vitro activation of the platelets. The choice of anticoagulant is one of the critical preanalytical conditions as anticoagulants exert different effects on the activation of platelets ex vivo. We tested the effectiveness of Diatube-H (also known as CTAD; sodium citrate, theophylline, adenosine and dipyridamole) and citrate vacutainer tubes in preventing artefactual activation of platelets and preserving functional reserve. Platelet surface expression of the CD62P (reflecting alpha granule release), CD63 (reflecting lysosomal release) and modulation of normal platelet membrane glycoproteins CD41a and CD42b, were measured in whole blood and in isolated platelets immediately after collection and at 6, 24 and 48 h after venipuncture. Samples taken into Diatube-H showed less spontaneous platelet activation than did those taken into citrate. To measure in vitro platelet functional reserve, thrombin was added as agonist to blood stored for varying periods up to 48 h. Although Diatube-H suppressed in vitro platelet activation for up to 4 h, in samples kept for 6-24 h before thrombin addition, the inhibitory effect was lost and platelets responded fully to agonist activation. Hence, Diatube-H preserved platelets and allowed for measurement of in vivo platelet activation as well as thrombin-induced in vitro platelet activation after 6-24 h, in both whole blood and isolated platelets.

  12. The causes and coping manners in the blood donation reaction of the apheresis platelet%机采血小板献血反应的原因分析与对策

    Institute of Scientific and Technical Information of China (English)

    林菊; 桑列勇; 杜冬芬; 李素娥

    2016-01-01

    Objective To investigate the causes and the treatments in the blood donation reaction of the apheresis platelet. Methods The intervention and nursing measures of 9 903 cases of apheresis platelet donors from January 2012 to November 2015 were summarized. A total of 53 blood donation responders′ data such as gender were collected, and the data were analyzed. Results From January 2012 to November 2015 blood donation reaction rate was 0.54% (53/903), which was lower than that reported in the literature. Among them, 41 cases were female and 12 were male, female blood donation reaction rate was higher than the male (χ2=78.36,P0.05). Blood donation reactions occurred in 34 cases within 5 minutes before the end of the program, accounting for 64.2%(34/53) of the total. Conclusions The sex and blood cell separator and coping of blood volume and the spiritual factors are related to blood donation reaction. Providing quality nursing and services, and creating a good environment for blood donors are conducive to prevent and reduce the occurrence of blood donation reaction.%目的:探讨机采血小板献血反应的发生原因及对策。方法总结2012年1月至2015年11月9903人次机采血小板献血者的干预及护理方法,收集53人次献血反应者性别等资料进行统计分析。结果2012年1月至2015年11月献血反应发生率为0.54%(53/9903);其中男12人次,女41人次,女性献血反应发生率高于男性(χ2=78.36,P0.05)。程序运行结束前5 min内发生献血反应34人次占64.2%。结论献血反应与性别、分离机型、处理血量、精神因素等有关,为献血者提供优质护理和服务,创造良好的献血环境,有利于预防和减少献血反应的发生。

  13. The utilization of adenosine triphosphate in rat mast cells during histamine release induced by anaphylactic reaction and compound 48/80

    DEFF Research Database (Denmark)

    Johansen, Torben; Chakravarty, N

    1975-01-01

    The ATP content of rat peritoneal mast cells has been studied in relation to histamine release induced by compound 48/80 and antigen-antibody (anaphylactic) reaction in vitro. When the ATP content of actively sensitized mast cells was reduced to different levels by oligomycin, a good correlation...... was obtained between the ATP levels and the amounts of histamine released by the anaphylactic reaction. A similar linear relation has previously been demonstrated between the ATP levels of mast cells and histamine release induced by compound 48/80. The ATP content of mast cells was also studied at different...... intervals after the exposure of the cells to antigen or compound 48/80. No significant change in the ATP content was observed in untreated mast cells during the short period when histamine release occurs. If, however, the mast cells were preincubated with oligomycin or 2-deoxyglucose to reduce the rate...

  14. Allogeneic Platelet Releasate Preparations Derived via a Novel Rapid Thrombin Activation Process Promote Rapid Growth and Increased BMP-2 and BMP-4 Expression in Human Adipose-Derived Stem Cells.

    Science.gov (United States)

    McLaughlin, Michael; Gagnet, Paul; Cunningham, Elizabeth; Yeager, Randi; D'Amico, Michael; Guski, Katie; Scarpone, Michael; Kuebler, Daniel

    2016-01-01

    The administration of human adipose-derived stem cells (ASCs) represents a promising regenerative therapy for the treatment of orthopedic injuries. While ASCs can be easily isolated from liposuction-derived adipose tissue, most clinical applications will likely require in vitro culture expansion of these cells using nonxenogeneic components. In this study, platelet releasate was generated using a novel rapid thrombin activation method (tPR). ASCs grown in media supplemented with tPR proliferated much faster than ASCs grown in media supplemented with 10% fetal bovine serum. The cells also retained the ability to differentiate along chondrogenic, adipogenic, and osteogenic lineages. The tPR cultured ASCs displayed elevated expression of BMP-4 (5.7 ± 0.97-fold increase) and BMP-2 (4.7 ± 1.3-fold increase) and decreased expression of PDGF-B (4.0 ± 1.4-fold decrease) and FGF-2 (33 ± 9.0-fold decrease). No significant changes in expression were seen with TGF-β and VEGF. This pattern of gene expression was consistent across different allogeneic tPR samples and different ASC lines. The use of allogeneic rapidly activated tPR to culture ASCs is associated with both an increased cell yield and a defined gene expression profile making it an attractive option for cell expansion prior to cell-based therapy for orthopedic applications.

  15. Allogeneic Platelet Releasate Preparations Derived via a Novel Rapid Thrombin Activation Process Promote Rapid Growth and Increased BMP-2 and BMP-4 Expression in Human Adipose-Derived Stem Cells

    Directory of Open Access Journals (Sweden)

    Michael McLaughlin

    2016-01-01

    Full Text Available The administration of human adipose-derived stem cells (ASCs represents a promising regenerative therapy for the treatment of orthopedic injuries. While ASCs can be easily isolated from liposuction-derived adipose tissue, most clinical applications will likely require in vitro culture expansion of these cells using nonxenogeneic components. In this study, platelet releasate was generated using a novel rapid thrombin activation method (tPR. ASCs grown in media supplemented with tPR proliferated much faster than ASCs grown in media supplemented with 10% fetal bovine serum. The cells also retained the ability to differentiate along chondrogenic, adipogenic, and osteogenic lineages. The tPR cultured ASCs displayed elevated expression of BMP-4 (5.7 ± 0.97-fold increase and BMP-2 (4.7 ± 1.3-fold increase and decreased expression of PDGF-B (4.0 ± 1.4-fold decrease and FGF-2 (33 ± 9.0-fold decrease. No significant changes in expression were seen with TGF-β and VEGF. This pattern of gene expression was consistent across different allogeneic tPR samples and different ASC lines. The use of allogeneic rapidly activated tPR to culture ASCs is associated with both an increased cell yield and a defined gene expression profile making it an attractive option for cell expansion prior to cell-based therapy for orthopedic applications.

  16. The functional role of platelets in the regulation of angiogenesis.

    Science.gov (United States)

    Walsh, Tony G; Metharom, Pat; Berndt, Michael C

    2015-01-01

    Functionally, platelets are primarily recognized as key regulators of thrombosis and hemostasis. Upon vessel injury, the typically quiescent platelet interacts with subendothelial matrix to regulate platelet adhesion, activation and aggregation, with subsequent induction of the coagulation cascade forming a thrombus. Recently, however, newly described roles for platelets in the regulation of angiogenesis have emerged. Platelets possess an armory of pro- and anti-angiogenic proteins, which are actively sequestered and highly organized in α-granule populations. Platelet activation facilitates their release, eliciting potent angiogenic responses through mechanisms that appear to be tightly regulated. In conjunction, the release of platelet-derived phospholipids and microparticles has also earned merit as synergistic regulators of angiogenesis. Consequently, platelets have been functionally implicated in a range of angiogenesis-dependent processes, including physiological roles in wound healing, vascular development and blood/lymphatic vessel separation, whilst facilitating aberrant angiogenesis in a range of diseases including cancer, atherosclerosis and diabetic retinopathy. Whilst the underlying mechanisms are only starting to be elucidated, significant insights have been established, suggesting that platelets represent a promising therapeutic strategy in diseases requiring angiogenic modulation. Moreover, anti-platelet therapies targeting thrombotic complications also exert protective effects in disorders characterized by persistent angiogenesis.

  17. Clinical application of radiolabelled platelets

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, C. (Medical Univ. Lubeck, Lubeck (DE))

    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.

  18. 2-Arachidonoylglycerol enhances platelet formation from human megakaryoblasts.

    Science.gov (United States)

    Gasperi, Valeria; Avigliano, Luciana; Evangelista, Daniela; Oddi, Sergio; Chiurchiù, Valerio; Lanuti, Mirko; Maccarrone, Mauro; Valeria Catani, Maria

    2014-01-01

    Platelets modulate vascular system integrity, and their loss is critical in haematological pathologies and after chemotherapy. Therefore, identification of molecules enhancing platelet production would be useful to counteract thrombocytopenia. We have previously shown that 2-arachidonoylglycerol (2-AG) acts as a true agonist of platelets, as well as it commits erythroid precursors toward the megakaryocytic lineage. Against this background, we sought to further interrogate the role of 2-AG in megakaryocyte/platelet physiology by investigating terminal differentiation, and subsequent thrombopoiesis. To this end, we used MEG-01 cells, a human megakaryoblastic cell line able to produce in vitro platelet-like particles. 2-AG increased the number of cells showing ruffled surface and enhanced surface expression of specific megakaryocyte/platelet surface antigens, typical hallmarks of terminal megakaryocytic differentiation and platelet production. Changes in cytoskeleton modeling also occurred in differentiated megakaryocytes and blebbing platelets. 2-AG acted by binding to CB1 and CB2 receptors, because specific antagonists reverted its effect. Platelets were split off from megakaryocytes and were functional: they contained the platelet-specific surface markers CD61 and CD49, whose levels increased following stimulation with a natural agonist like collagen. Given the importance of 2-AG for driving megakaryopoiesis and thrombopoiesis, not surprisingly we found that its hydrolytic enzymes were tightly controlled by classical inducers of megakaryocyte differentiation. In conclusion 2-AG, by triggering megakaryocyte maturation and platelet release, may have clinical efficacy to counteract thrombocytopenia-related diseases.

  19. Analysis of aggregation of platelets in thrombosis

    Science.gov (United States)

    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.

  20. Patients with previous definite stent thrombosis have a larger fraction of immature platelets and a reduced antiplatelet effect of aspirin

    DEFF Research Database (Denmark)

    Würtz, Morten; Grove, Erik; Wulff, Lise Nielsen;

    turnover. Key Words: aspirin; immature platelets; platelet aggregation; platelet function tests; stent thrombosis Abbreviations: ARU, aspirin reaction units; AU, aggregation units; BMS, bare-metal stent(s); DES, drug-eluting stent(s); IPF, immature platelet fraction; MEA, multiple electrode aggregometry...

  1. 富血小板纤维蛋白体外释放TGF-β1浓度的探讨%To investigate the concentration of platelet-rich fibrin releasing transforming growth factor-β1 in vitro

    Institute of Scientific and Technical Information of China (English)

    陈诚; 张文丽; 李淑慧; 李一鸣; 周晶; 吴佩玲

    2014-01-01

    Objective:We detected the concentration of transforming growth factor-β1 in platelet-rich fibrin,to find the tendency that platelet-rich fibrin releasing TGF-β1 in vitro. Method:Blood was taken from central artery of rabbits,to preparation the film of PRF at 3000 r/min for 10 minutes.Add them to five milliliters of fresh DMEM,the time points to col-lect exudates was in day 7,14,21,28 at 37 ℃. And detect the TGF-β1 concentration by ELISA. Result:The mass concen-tration of TGF-β1 in PRF is increases with the increasing of time,at its peak to 28 days,TGF-β1 mass concentration in 21~28 days shows the tendency of a significantly higher. Conclusion:Different time have a certain influence on the mass con-centration of TGF-β1 in PRF exudates changes.With the increase of time, the concentration of TGF-β1 increased gradually.%目的:通过检测富血小板纤维蛋白(PRF)中转化生长因子-β1的浓度,了解PRF体外释放效用因子TGF-β1的趋势。方法:兔耳中央动脉抽血,离心3000 r/min×10 min,制取PRF膜,置于5 mL新鲜DMEM溶液中,分别于37℃下静置7 d、14 d、21 d、28 d收集析出液。ELISA法检测其浓度。结果:PRF析出液中TGF-β1质量浓度随着时间的递增而增大,至28 d时达到高峰,TGF-β1质量浓度在21~28 d时呈现一个显著增高的趋势。结论:不同时间对PRF析出液中TGF-β1的质量浓度变化存在一定的影响,随着时间的增加,TGF-β1的浓度逐渐增大。

  2. Transcellular lipoxygenase metabolism between monocytes and platelets

    Energy Technology Data Exchange (ETDEWEB)

    Bigby, T.D.; Meslier, N. (Univ. of California, San Francisco (USA))

    1989-09-15

    We have examined the effects of co-culture and in vitro co-stimulation on lipoxygenase metabolism in monocytes and platelets. Monocytes were obtained from the peripheral blood of normal volunteers by discontinuous gradient centrifugation and adherence to tissue culture plastic. Platelets were obtained from the platelet-rich plasma of the same donor. When 10(9) platelets and 2.5 x 10(6) monocytes were co-stimulated with 1 microM A23187, these preparations released greater quantities of 12(S)-hydroxy-10-trans-5,8,14-cis-eicosatetraenoic acid, 5(S),12-(S)dihydroxy-6,10-trans-8,14-cis-eicosatetraenoic acid, and leukotriene C4, 5(S)-hydroxy-6(R)-S-glutathionyl-7,9-trans-11,14-cis-eicosatetraenoic (LTC4) when compared with monocytes alone. Release of arachidonic acid, 5-HETE, delta 6-trans-LTB4, and delta 6-trans-12-epi-LTB4 from monocytes was decreased in the presence of platelets. A dose-response curve was constructed and revealed that the above changes became evident when the platelet number exceeded 10(7). Dual radiolabeling experiments with 3H- and 14C-arachidonic acid revealed that monocytes provided arachidonic acid, 5-HETE, and LTA4 for further metabolism by the platelet. Monocytes did not metabolize platelet intermediates detectably. In addition, as much as 1.2 microM 12(S)-hydroxy-10-trans-5,8,14-cis-eicosatetraenoic acid and 12(S)-hydroperoxy-10-trans-5,8,14-cis-eicosatetraenoic acid had no effect on monocyte lipoxygenase metabolism. Platelets were capable of converting LTA4 to LTC4, but conversion of LTA4 to LTB4 was not detected. We conclude that the monocyte and platelet lipoxygenase pathways undergo a transcellular lipoxygenase interaction that differs from the interaction of the neutrophil and platelet lipoxygenase pathways. In this interaction monocytes provide intermediate substrates for further metabolic conversion by platelets in an unidirectional manner.

  3. [Erythrocytes infected by Plasmodium falciparum activate human platelets].

    Science.gov (United States)

    Polack, B; Peyron, F; Sheick Zadiuddin, I; Kolodié, L; Ambroise-Thomas, P

    1990-01-01

    Blood platelets are involved in Plasmodium falciparum malaria pathology as shown by thrombocytopenia and increased plasma level of two alpha granule proteins: beta thromboglobulin (beta TG) and platelet factor 4 (PF4). In this study we demonstrate that Plasmodium falciparum parasitized erythrocytes activate directly the secretion of beta TG and PF4 by human platelets. This secretion is related to parasitemia and occurs immediately after contact. Treatment of parasited erythrocytes by trypsin and diffusion chamber experiments suggest that platelet activation is triggered by parasitic substances shed on erythrocyte membrane and released in the culture medium.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  5. Pooled platelet concentrates: an alternative to single donor apheresis platelets?

    Science.gov (United States)

    Pietersz, R N I

    2009-10-01

    Three types of platelet concentrates (PC) are compared: PC either processed with the platelet-rich plasma (PRP) or the Buffy coat (BC) method from whole blood units and PC obtained by apheresis. Leuko-reduction (LR) pre-storage is advocated to improve quality of the PC during storage and reduce adverse reactions in recipients. Standardization of methods allow preparation of PC with comparable yields of approximately 400 x 10(9) platelets in pooled non-LR-PRP, approximately 370 x 10(9) in pooled LR-BC-PC and in LR apheresis PC the number of platelets can be targeted on 350 x 10(9) or more with devices of various manufacturers. While viral transmission can be prevented by outstanding laboratory tests, the risk of bacterial contamination should be reduced by improved arm disinfection, deviation of the first 20-30 ml of blood and culture or rapid detection assays of the PC pre-issue. In a large prospective multicenter trial no significant difference was observed between cultures of apheresis PC (n = 15,198): 0.09% confirmed positive units versus 0.06% in pooled BC-PC (n = 37,045), respectively. Though platelet activation as measured by CD62 expression may differ in vitro in PC obtained with various apheresis equipment, and also between PC processed with the two whole blood methods there is scarce literature about the clinical impact of these findings. In conclusion the final products of LR-PC derived from whole blood or obtained by apheresis can be comparable, provided the critical steps of the processing method are identified and covered and the process is in control.

  6. Rethinking platelet function: thrombocytopenia induced immunodeficiency in critical illness

    DEFF Research Database (Denmark)

    Ostrowski, Sisse R; Johansson, Per Ingemar

    2011-01-01

    traditional innate immune cells, platelets are recruited immediately into injured and inflamed tissue, they release immune mediators, express and shed immunologically active membrane receptors, they interact with other immune cells and they recognize and clear pathogens. We hypothesize that thrombocytopenia...

  7. Extended Storage of Pathogen-Reduced Platelet Concentrates (PRECON)

    Science.gov (United States)

    2016-10-01

    described in the original statement of work, Extended Storage of Pathogen-Reduced Platelet Concentrates (PRECON). 1. Determine the optimum conditions...platelet infusion, the subject will be carefully monitored for adverse reactions; i.e., fever , chills, dyspnea, urticaria or pain (infusion site, chest...adverse reactions; e.g., fever , chills, dyspnea, urticaria, or pain (infusion site, chest pain or other). Adverse reactions will be recorded in the

  8. Platelets and hemostasis

    Directory of Open Access Journals (Sweden)

    M. A. Panteleev

    2014-09-01

    Full Text Available Platelets are anuclear cell fragments playing important role in hemostasis, termination of bleeding after damage, as well as in pathological thrombus formation. The main action of platelets is the formation of aggregates, overlapping the injury. They obtained the ability to aggregate by the transition process called activation. Despite the relatively simple and definite function platelet structure is very difficult: they have almost a full set of organelles, including the endoplasmic reticulum, mitochondria and other entities. When activated platelets secrete various granules interact with plasma proteins and red blood cells and other tissues. Their activation is controlled by multiple receptors and complex signaling cascades. In this review platelet structure, mechanisms of its functioning in health and disease, diagnostic methods of platelet function and approaches to their correction were considered. Particular attention will be given to those areas of the science of platelets, which still lay hidden mysteries.

  9. Effects of pathogen reduction systems on platelet microRNAs, mRNAs, activation, and function.

    Science.gov (United States)

    Osman, Abdimajid; Hitzler, Walter E; Meyer, Claudius U; Landry, Patricia; Corduan, Aurélie; Laffont, Benoit; Boilard, Eric; Hellstern, Peter; Vamvakas, Eleftherios C; Provost, Patrick

    2015-01-01

    Pathogen reduction (PR) systems for platelets, based on chemically induced cross-linking and inactivation of nucleic acids, potentially prevent transfusion transmission of infectious agents, but can increase clinically significant bleeding in some clinical studies. Here, we documented the effects of PR systems on microRNA and mRNA levels of platelets stored in the blood bank, and assessed their impact on platelet activation and function. Unlike platelets subjected to gamma irradiation or stored in additive solution, platelets treated with Intercept (amotosalen+ ultraviolet-A [UVA] light) exhibited significantly reduced levels of 6 of the 11 microRNAs, and 2 of the 3 anti-apoptotic mRNAs (Bcl-xl and Clusterin) that we monitored, compared with platelets stored in plasma. Mirasol (riboflavin+ UVB light) treatment of platelets did not produce these effects. PR neither affected platelet microRNA synthesis or function nor induced cross-linking of microRNA-sized endogenous platelet RNA species. However, the reduction in the platelet microRNA levels induced by Intercept correlated with the platelet activation (p platelet aggregation response to ADP (p platelet activation, resulting in the release of microRNAs and mRNAs from platelets. The clinical implications of this reduction in platelet nucleic acids secondary to Intercept remain to be established.

  10. Generation of functional platelets from canine induced pluripotent stem cells.

    Science.gov (United States)

    Nishimura, Toshiya; Hatoya, Shingo; Kanegi, Ryoji; Sugiura, Kikuya; Wijewardana, Viskam; Kuwamura, Mitsuru; Tanaka, Miyuu; Yamate, Jyoji; Izawa, Takeshi; Takahashi, Masahiro; Kawate, Noritoshi; Tamada, Hiromichi; Imai, Hiroshi; Inaba, Toshio

    2013-07-15

    Thrombocytopenia (TTP) is a blood disease common to canines and human beings. Currently, there is no valid therapy for this disease except blood transfusion. In this study, we report the generation of canine induced pluripotent stem cells (ciPSCs) from canine embryonic fibroblasts, and a novel protocol for creating mature megakaryocytes (MKs) and functional platelets from ciPSCs. The ciPSCs were generated using lentiviral vectors, and differentiated into MKs and platelets on OP9 stromal cells supplemented with growth factors. Our ciPSCs presented in a tightly domed shape and showed expression of a critical pluripotency marker, REX1, and normal karyotype. Additionally, ciPSCs differentiated into cells derived from three germ layers via the formation of an embryoid body. The MKs derived from ciPSCs had hyperploidy and transformed into proplatelets. The proplatelets released platelets early on that expressed specific MK and platelet marker CD41/61. Interestingly, these platelets, when activated with adenosine diphosphate or thrombin, bind to fibrinogen. Moreover, electron microscopy showed that the platelets had the same ultrastructure as peripheral platelets. Thus, we have demonstrated for the first time the generation of ciPSCs that are capable of differentiating into MKs and release functional platelets in vitro. Our system for differentiating ciPSCs into MKs and platelets promises a critical therapy for canine TTP and appears to be extensible in principle to resolve human TTP.

  11. Alloantibody induced platelet responses in transplants: potent mediators in small packages.

    Science.gov (United States)

    Kuo, Hsiao-Hsuan; Morrell, Craig N; Baldwin, William M

    2012-12-01

    The early histological studies of organ allografts noted platelets attached to vascular endothelium. Platelets adhere to vessels before any morphological evidence of endothelial injury. Subsequently, in vitro and in vivo experiments have demonstrated that alloantibodies can induce exocytosis of von Willebrand factor and P-selectin from endothelial cells and attachment of platelets within minutes. Platelets also adhere to and stimulate leukocytes. These interactions are increased by complement activation. After attachment platelets degranulate, releasing preformed mediators. Some chemokines stored together in platelet granules can form heteromers with synergistic functions. Heteromers containing platelet factor 4 (PF4; CXCL4) are specific to platelets and provide insights to unique platelet functions and opportunities for therapeutic intervention.

  12. Hemostatic Function of Apheresis Platelets Stored at 4 deg C and 22 deg C

    Science.gov (United States)

    2014-05-01

    activation: CD62P is released from platelet !- granules ; PS is externalized from the inner leaflet of the platelet membrane; and CD40L is a FIG. 4. Enzyme...HEMOSTATIC FUNCTION OF APHERESIS PLATELETS STORED AT 4-C AND 22-C Kristin M. Reddoch,* Heather F. Pidcoke,† Robbie K. Montgomery,† Chriselda G. Fedyk...in final form 23 Oct 2013 ABSTRACT Introduction: Platelet refrigeration decreases the risk of bacterial contamination and may preserve function better

  13. Pathogenic role of platelets in rheumatoid arthritis and systemic autoimmune diseases

    OpenAIRE

    Harifi, Ghita; SIBILIA, JEAN

    2016-01-01

    Well-recognized for their role in vascular homoeostasis, platelets may play a major role in inflammation and immunomodulation. Substantial data are emerging on the pathogenic involvement of platelets in inflammatory arthritis and autoimmune diseases, indicating the existence of crosstalk between the coagulation and inflammation system. Upon activation, platelets release pro-inflammatory platelets microparticles, which interact with leucocytes leading to joint and systemic inflammation in rheu...

  14. Regulation of corticotropin releasing hormone receptor type 1 messenger RNA level in Y-79 retinoblastoma cells: potential implications for human stress response and immune/inflammatory reaction

    Directory of Open Access Journals (Sweden)

    N. C. Vamvakopoulos

    1996-01-01

    Full Text Available We report the regulation of type 1 receptor mRNA in Y-79 human retinoblastoma cells, grown in the absence or presence of pharmacological levels of phorbol esters, forskolin, glucocorticoids and their combinations. To control for inducibility and for assessing the sensitivity of the Y-79 system to glucocorticoids, corticotropin releasing hormone mRNA levels were measured in parallel. All treatments stimulated corticotropin releasing hormone receptor type 1 gene expression relative to baseline. A weak suppression of corticotropin releasing hormone mRNA level was observed during dexamethasone treatment. The cell line expressed ten-fold excess of receptor to ligand mRNA under basal conditions. The findings predict the presence of functional phorbol ester, cyclic AMP and glucocorticoid response elements in the promoter region of corticotropin releasing hormone receptor type 1 gene and support a potential role for its product during chronic stress and immune/inflammatory reaction.

  15. Transporters in human platelets: physiologic function and impact for pharmacotherapy.

    Science.gov (United States)

    Jedlitschky, Gabriele; Greinacher, Andreas; Kroemer, Heyo K

    2012-04-12

    Platelets store signaling molecules (eg, serotonin and ADP) within their granules. Transporters mediate accumulation of these molecules in platelet granules and, on platelet activation, their translocation across the plasma membrane. The balance between transporter-mediated uptake and elimination of signaling molecules and drugs in platelets determines their intracellular concentrations and effects. Several members of the 2 major transporter families, ATP-binding cassette (ABC) transporters and solute carriers (SLCs), have been identified in platelets. An example of an ABC transporter is MRP4 (ABCC4), which facilitates ADP accumulation in dense granules. MRP4 is a versatile transporter, and various additional functions have been proposed, notably lipid mediator release and a role in aspirin resistance. Several other ABC proteins have been detected in platelets with functions in glutathione and lipid homeostasis. The serotonin transporter (SERT, SLC6A4) in the platelet plasma membrane represents a well-characterized example of the SLC family. Moreover, recent experiments indicate expression of OATP2B1 (SLCO2B1), a high affinity transporter for certain statins, in platelets. Changes in transporter localization and expression can affect platelet function and drug sensitivity. This review summarizes available data on the physiologic and pharmacologic role of transporters in platelets.

  16. Acidosis downregulates platelet haemostatic functions and promotes neutrophil proinflammatory responses mediated by platelets.

    Science.gov (United States)

    Etulain, Julia; Negrotto, Soledad; Carestia, Agostina; Pozner, Roberto Gabriel; Romaniuk, María Albertina; D'Atri, Lina Paola; Klement, Giannoula Lakka; Schattner, Mirta

    2012-01-01

    Acidosis is one of the hallmarks of tissue injury such as trauma, infection, inflammation, and tumour growth. Although platelets participate in the pathophysiology of all these processes, the impact of acidosis on platelet biology has not been studied outside of the quality control of laboratory aggregation assays or platelet transfusion optimization. Herein, we evaluate the effect of physiologically relevant changes in extracellular acidosis on the biological function of platelets, placing particular emphasis on haemostatic and secretory functions. Platelet haemostatic responses such as adhesion, spreading, activation of αIIbβ3 integrin, ATP release, aggregation, thromboxane B2 generation, clot retraction and procoagulant activity including phosphatidilserine exposure and microparticle formation, showed a statistically significant inhibition of thrombin-induced changes at pH of 7.0 and 6.5 compared to the physiological pH (7.4). The release of alpha granule content was differentially regulated by acidosis. At low pH, thrombin or collagen-induced secretion of vascular endothelial growth factor and endostatin were dramatically reduced. The release of von Willebrand factor and stromal derived factor-1α followed a similar, albeit less dramatic pattern. In contrast, the induction of CD40L was not changed by low pH, and P-selectin exposure was significantly increased. While the generation of mixed platelet-leukocyte aggregates and the increased chemotaxis of neutrophils mediated by platelets were further augmented under acidic conditions in a P-selectin dependent manner, the increased neutrophil survival was independent of P-selectin expression. In conclusion, our results indicate that extracellular acidosis downregulates most of the haemostatic platelet functions, and promotes those involved in amplifying the neutrophil-mediated inflammatory response.

  17. Role of blood platelets in infection and inflammation.

    Science.gov (United States)

    Klinger, Matthias H F; Jelkmann, Wolfgang

    2002-09-01

    Blood platelets are here presented as active players in antimicrobial host defense and the induction of inflammation and tissue repair in addition to their participation in hemostasis. Megakaryopoiesis is inhibited after acute infection with viruses or bacteria. In contrast, chronic inflammation is often associated with reactive thrombocytosis. Platelets can bind and internalize pathogens and release microbicidal proteins that kill certain bacteria and fungi. By making cell-cell contacts with leukocytes and endothelial cells, platelets assist white blood cells in rolling, arrest and transmigration. On stimulation by bacteria or thrombin, platelets release the content of their alpha-granules, which include an arsenal of bioactive peptides, such as CC-chemokines and CXC-chemokines and growth factors for endothelial cells, smooth muscle cells and fibroblasts. Thus, integral to innate immunity, the tiny little platelets may become bombshells when irritated by pathogens.

  18. Microvesicles from platelets: novel drivers of vascular inflammation.

    Science.gov (United States)

    Vajen, T; Mause, S F; Koenen, R R

    2015-08-01

    Microvesicles are receiving increased attention not only as biomarkers but also as mediators of cell communication and as integral effectors of disease. Platelets present a major source of microvesicles and release these microvesicles either spontaneously or upon activation. Platelet-derived microvesicles retain many features of their parent cells and have been shown to exert modulatory effects on vascular and immune cells. Accordingly, microvesicles from platelets can be measured at increased levels in patients with cardiovascular disease or individuals at risk. In addition, isolated microvesicles from platelets were shown to exert immunomodulatory actions on various cell types. In this review the various aspects of platelet-derived microvesicles including release, clearance, measurement, occurrence during disease and relevance for the pathophysiology of vascular inflammation will be discussed.

  19. Alterations of adenine nucleotide metabolism and function of blood platelets in patients with diabetes.

    Science.gov (United States)

    Michno, Anna; Bielarczyk, Hanna; Pawełczyk, Tadeusz; Jankowska-Kulawy, Agnieszka; Klimaszewska, Joanna; Szutowicz, Andrzej

    2007-02-01

    Increased activity of blood platelets contributes to vascular complications in patients with diabetes. The aim of this work was to investigate whether persisting hyperglycemia in diabetic patients generates excessive accumulation of ATP/ADP, which may underlie platelet hyperactivity. Platelet ATP and ADP levels, thiobarbituric acid-reactive species synthesis, and aggregation of platelets from patients with diabetes were 18-82% higher than in platelets from healthy participants. In patients with diabetes, platelet stimulation with thrombin caused about two times greater release of ATP and ADP than in the healthy group while decreasing intraplatelet nucleotide content to similar levels in both groups. This indicates that the increased content of adenylate nucleotides in the releasable pool in the platelets of diabetic patients does not affect their level in metabolic cytoplasmic/mitochondrial compartments. Significant correlations between platelet ATP levels and plasma fructosamine, as well as between platelet ATP/ADP and platelet activities, have been found in diabetic patients. In conclusion, chronic hyperglycemia-evoked elevations of ATP/ADP levels and release from blood platelets of patients with diabetes may be important factors underlying platelet hyperactivity in the course of the disease.

  20. Role of nitric oxide synthase in collagen-platelet interaction: involvement of platelet nonintegrin collagen receptor nitrotyrosylation.

    Science.gov (United States)

    Chiang, T M; Cole, F; Woo-Rasberry, V; Kang, E S

    2001-05-15

    Platelets possess the endothelial isoform of nitric oxide synthase (eNOS), which plays an important role in platelet function. Other laboratories, including ours, have reported that nitric oxide (NO) is released upon exposure of platelets to collagen, but the mechanism of the interaction is not yet established. The objective of this study is to examine the possible role of nonintegrin receptor nitrotyrosylation on collagen-induced platelet aggregation. Results of the study show that two platelet proteins with M(r) of 65- and 23-kDa proteins are nitrotyrosylated in a time-dependent manner after the addition of type I collagen. The M(r) 65-kDa protein is identified as the platelet receptor for type I collagen. The recombinant protein of the platelet receptor for type I collagen can also be nitrotyrosylated. The nitrotyrosylated recombinant protein loses its ability to inhibit type I collagen-induced platelet aggregation. In addition, the polyclonal anti-65 kDa immunoprecipitates eNOS suggesting that the platelet nonintegrin receptor for type I collagen is closely linked to the eNOS. These results demonstrate that the inhibitory effect of NO on collagen-induced platelet aggregation may be mediated by the nitrotyrosylation of the 65-kDa receptor.

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

    Science.gov (United States)

    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

  2. Platelets stimulate fibroblast-mediated contraction of collagen gels

    Directory of Open Access Journals (Sweden)

    Lundahl Joachim

    2003-10-01

    Full Text Available Abstract Background Platelets are thought to play a role in a variety of inflammatory conditions in the lung, some of which may lead to fibrosis. In the current study we tested the hypothesis that whole platelets and platelet lysate can mediate remodelling of extracellular matrix in vitro by affecting fibroblast-mediated contraction of a collagen gel. We also sought to determine to what extent platelet-derived growth factor (PDGF and transforming growth factor-β (TGF-β contribute to this effect. Methods Washed platelets, isolated from healthy blood donors, and platelet lysate (freezing and thawing, were cast together with human lung fibroblasts in three-dimensional collagen gels. The gels were then released and cultured for four days. PDGF and TGF-β1 concentrations were measured in culture supernatants by ELISA. Results Both platelets and platelet lysate augmented fibroblast-mediated gel contraction in a time and concentration dependent manner (19.9% ± 0.1 (mean ± SEM of initial area vs. 48.0% ± 0.4 at 48 hours; P 1 and PDGF-AA/AB were released in co-culture. PDGF-AA/AB had a maximum release at 24 hours whereas TGF-β1 release increased with longer culture periods. Neutralising antibodies to these mediators partially inhibited platelet-induced gel contraction. Conclusion We conclude that platelets may promote remodelling of extracellular matrix in vitro and that PDGF and TGF-β partially mediate this effect, also indicating a role for other mediators. The findings may be an important mechanism in regulating repair processes after injury.

  3. Structure-activity relationship of a series of 17 parabens and related compounds for histamine release in rat peritoneal mast cells and skin allergic reaction in guinea pigs.

    Science.gov (United States)

    Uramaru, Naoto; Inoue, Toshio; Watanabe, Yoko; Shigematsu, Hidenari; Ohta, Shigeru; Kitamura, Shigeyuki

    2014-02-01

    Parabens, which are a homologous series of esters of p-hydroxybenzoic acid, have been used as preservatives in cosmetics, medicines and foods because of their antimicrobial activity. However, parabens in cosmetics have been suspected to cause allergic contact dermatitis. In this study, we examined paraben-induced histamine release from rat peritoneal mast cells and skin reaction in guinea pigs using a series of 17 parabens with different alcohol side chains, ranging from methylparaben to dodecylparaben. Octylparaben showed the greatest histamine release-inducing activity from mast cells, and the activity was decreased in shorter- and longer-side-chain parabens. Octyl benzoate, octyl o-hydroxybenzoate and phenyloctane caused no significant degranulation of mast cells, whereas octyl m-hydroxybenzoate, octyl p-hydroxybenzoate and octyl phenol induced concentration-related degranulation. Metabolites of these parabens (p-hydroxybenzoic acid and alcohols) did not show histamine release-inducing activity. In the guinea pig skin reaction test, heptylparaben induced a typical strong skin reaction, while butylparaben induced a typical weak skin reaction, and methylparaben and dodecylparaben were inactive. Metabolites of parabens (p-hydroxybenzoic acid and alcohols) were also inactive. These results indicate that interaction of parabens with rat mast cells requires a minimum length and adequate lipophilicity of the alkyl side chain. Since metabolites of parabens were inactive, parabens appear to be direct-acting allergens.

  4. A novel inflammatory role for platelets in sickle cell disease.

    Science.gov (United States)

    Davila, Jennifer; Manwani, Deepa; Vasovic, Ljiljana; Avanzi, Mauro; Uehlinger, Joan; Ireland, Karen; Mitchell, W Beau

    2015-01-01

    The severe pain, ischemia and organ damage that characterizes sickle cell disease (SCD) is caused by vaso-occlusion, which is the blockage of blood vessels by heterotypic aggregates of sickled erythrocytes and other cells. Vaso-occlusion is also a vasculopathy involving endothelial cell dysfunction, leukocyte activation, platelet activation and chronic inflammation resulting in the multiple adhesive interactions between cellular elements. Since platelets mediate inflammation as well as thrombosis via release of pro- and anti-inflammatory molecules, we hypothesized that platelets may play an active inflammatory role in SCD by secreting increased amounts of cytokines. Since platelets have been shown to contain mRNA and actively produce proteins, we also hypothesized that SCD platelets may contain increased cytokine mRNA. In this cross-sectional study, we sought to compare both the quantity of cytokines secreted and the cytokine mRNA content, between SCD and control platelets. We measured the secretion of Th1, Th2, and Th17-related cytokines from platelets in a cohort of SCD patients. We simultaneously measured platelet mRNA levels of those cytokines. Platelets from SCD patients secreted increased quantities of IL-1β, sCD40L, and IL-6 compared to controls. Secretion was increased in patients with alloantibodies. Additionally, mRNA of those cytokines was increased in SCD platelets. Platelets from sickle cell patients secrete increased amounts of inflammatory cytokines, and contain increased cytokine mRNA. These findings suggest a novel immunological role for platelets in SCD vasculopathy, in addition to their thrombotic role, and strengthen the rationale for the use of anti-platelet therapy in SCD.

  5. Environmentally benign graphite intercalation compound composition for exfoliated graphite, flexible graphite, and nano-scaled graphene platelets

    Science.gov (United States)

    Zhamu, Aruna; Jang, Bor Z.

    2014-06-17

    A carboxylic-intercalated graphite compound composition for the production of exfoliated graphite, flexible graphite, or nano-scaled graphene platelets. The composition comprises a layered graphite with interlayer spaces or interstices and a carboxylic acid residing in at least one of the interstices, wherein the composition is prepared by a chemical oxidation reaction which uses a combination of a carboxylic acid and hydrogen peroxide as an intercalate source. Alternatively, the composition may be prepared by an electrochemical reaction, which uses a carboxylic acid as both an electrolyte and an intercalate source. Exfoliation of the invented composition does not release undesirable chemical contaminants into air or drainage.

  6. Modulation of histamine release by fatty acids. A new in vitro model investigating adverse drug reactions in various species

    OpenAIRE

    Ennis, M.; Lorenz, Wilfried

    1985-01-01

    Histamine release caused by drugs and/or their solvents is a well known phenomenon. In this study, both in vivo (anaesthetized and conscious dogs) and in vitro (isolated rat peritoneal, human and guinea-pig lung mast cells) models were used. Cremophor E1 and six derivatives of 12-hydroxystearic acid were compared for their histamine releasing abilities. Although the three types of isolated mast cells responded similarly, histamine release being observed with DH (the diester of 12-hydroxystear...

  7. Platelets and Platelet-Derived Microvesicles as Immune Effectors in Type 2 Diabetes.

    Science.gov (United States)

    Cortez-Espinosa, Nancy; Mayoral, Laura Perez-Campos; Perez-Campos, Eduardo; Cabrera Fuentes, Hector Alejandro; Mayoral, Eduardo Perez-Campos; Martínez-Cruz, Ruth; Canseco, Socorro Pina; Andrade, Gabriel Mayoral; Cruz, Margarito Martinez; Velasco, Itandehui Gallegos; Cruz, Pedro Hernandez

    2017-01-01

    The association between type 2 diabetes mellitus (T2DM) and systemic inflammation may increase platelet reactivity and the accelerated development of vascular disease. Platelets are able to modulate the function of immune cells via the direct release of growth factors and pro-inflammatory chemokines through the production of microvesicles. The microvesicles trigger a transcellular delivery system of bioactive molecules to other cells acting as vectors in the exchange of biological information. Here, we consider the influence of platelets and platelet-derived microvesicles on cells of the immune system and the implications in the pathogenesis of T2DM. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  8. An alternative reaction for heme degradation catalyzed by the Escherichia coli O157:H7 ChuS protein: Release of hematinic acid, tripyrrole and Fe(III).

    Science.gov (United States)

    Ouellet, Yannick H; Ndiaye, Cheikh Tidiane; Gagné, Stéphane M; Sebilo, Anne; Suits, Michael D L; Jubinville, Éric; Jia, Zongchao; Ivancich, Anabella; Couture, Manon

    2016-01-01

    As part of the machinery to acquire, internalize and utilize heme as a source of iron from the host, some bacteria possess a canonical heme oxygenase, where heme plays the dual role of substrate and cofactor, the later catalyzing the cleavage of the heme moiety using O2 and electrons, and resulting in biliverdin, carbon monoxide and ferrous non-heme iron. We have previously reported that the Escherichia coli O157:H7 ChuS protein, which is not homologous to heme oxygenases, can bind and degrade heme in a reaction that releases carbon monoxide. Here, we have pursued a detailed characterization of such heme degradation reaction using stopped-flow UV-visible absorption spectrometry, the characterization of the intermediate species formed in such reaction by EPR spectroscopy and the identification of reaction products by NMR spectroscopy and Mass spectrometry. We show that hydrogen peroxide (in molar equivalent) is the key player in the degradation reaction, at variance to canonical heme oxygenases. While the initial intermediates of the reaction of ChuS with hydrogen peroxide (a ferrous keto π neutral radical and ferric verdoheme, both identified by EPR spectroscopy) are in common with heme oxygenases, a further and unprecedented reaction step, involving the cleavage of the porphyrin ring at adjacent meso-carbons, results in the release of hematinic acid (a monopyrrole moiety identified by NMR spectroscopy), a tripyrrole product (identified by Mass spectrometry) and non-heme iron in the ferric oxidation state (identified by EPR spectroscopy). Overall, the unprecedented reaction of E. coli O157:H7 ChuS provides evidence for a novel heme degradation activity in a Gram-negative bacterium.

  9. Hydrogen release reactions of Al-based complex hydrides enhanced by vibrational dynamics and valences of metal cations.

    Science.gov (United States)

    Sato, T; Ramirez-Cuesta, A J; Daemen, L; Cheng, Y-Q; Tomiyasu, K; Takagi, S; Orimo, S

    2016-09-27

    Hydrogen release from Al-based complex hydrides composed of metal cation(s) and [AlH4](-) was investigated using inelastic neutron scattering viewed from vibrational dynamics. The hydrogen release followed the softening of translational and [AlH4](-) librational modes, which was enhanced by vibrational dynamics and the valence(s) of the metal cation(s).

  10. Dengue virus binding and replication by platelets.

    Science.gov (United States)

    Simon, Ayo Y; Sutherland, Michael R; Pryzdial, Edward L G

    2015-07-16

    Dengue virus (DENV) infection causes ∼200 million cases of severe flulike illness annually, escalating to life-threatening hemorrhagic fever or shock syndrome in ∼500,000. Although thrombocytopenia is typical of both mild and severe diseases, the mechanism triggering platelet reduction is incompletely understood. As a probable initiating event, direct purified DENV-platelet binding was followed in the current study by quantitative reverse transcription-polymerase chain reaction and confirmed antigenically. Approximately 800 viruses specifically bound per platelet at 37°C. Fewer sites were observed at 25°C, the blood bank storage temperature (∼350 sites), or 4°C, known to attenuate virus cell entry (∼200 sites). Dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN) and heparan sulfate proteoglycan were implicated as coreceptors because only the combination of anti-DC-SIGN and low-molecular-weight heparin prevented binding. Interestingly, at 37°C and 25°C, platelets replicated the positive sense single-stranded RNA genome of DENV by up to ∼4-fold over 7 days. Further time course experiments demonstrated production of viral NS1 protein, which is known to be highly antigenic in patient serum. The infectivity of DENV intrinsically decayed in vitro, which was moderated by platelet-mediated generation of viable progeny. This was shown using a transcription inhibitor and confirmed by freeze-denatured platelets being incapable of replicating the DENV genome. For the first time, these data demonstrate that platelets directly bind DENV saturably and produce infectious virus. Thus, expression of antigen encoded by DENV is a novel consideration in the pathogen-induced thrombocytopenia mechanism. These results furthermore draw attention to the possibility that platelets may produce permissive RNA viruses in addition to DENV.

  11. Epithelial sodium channel modulates platelet collagen activation.

    Science.gov (United States)

    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.

  12. Influence of platelet-derived growth factor-AB on tissue development in autologous platelet-rich plasma gels.

    Science.gov (United States)

    Wirz, Simone; Dietrich, Maren; Flanagan, Thomas C; Bokermann, Gudrun; Wagner, Wolfgang; Schmitz-Rode, Thomas; Jockenhoevel, Stefan

    2011-07-01

    Fibrin-based scaffolds are widely used in tissue engineering. We postulated that the use of platelet-rich plasma (PRP) in contrast to platelet-poor plasma and pure fibrinogen as the basic material leads to an increased release of autologous platelet-derived growth factor (PDGF)-AB, which may have a consequent positive effect on tissue development. Therefore, we evaluated the release of PDGF-AB during the production process and the course of PDGF release during cultivation of plasma gels with and w/o platelets. The influence of PDGF-AB on the proliferation rate of human umbilical cord artery smooth muscle cells (HUASMCs) was studied using XTT assay. The synthesis of extracellular matrix by HUASMCs in plasma- and fibrin gels was measured using hydroxyproline assay. The use of PRP led to an increase in autologous PDGF-AB release. Further, the platelet-containing plasma gels showed a prolonged release of growth factor during cultivation. Both PRP and platelet-poor plasma gels had a positive effect on the production of collagen. However, PDGF-AB as a supplement in medium and in pure fibrin gel had neither an effect on cell proliferation nor on the collagen synthesis rate. This observation may be due to an absence of PDGF receptors in HUASMCs as determined by flow cytometry. In conclusion, although the prolonged autologous production of PDGF-AB in PRP gels is possible, the enhanced tissue development by HUASMCs within such gels is not PDGF related.

  13. The detection of platelet isoantibodies by membrane immunofluorescence.

    Science.gov (United States)

    van der Schans, G S; Veenhoven, W A; Snijder, J A; Nieweg, H O

    1977-07-01

    A membrane ummunofluorescence test for the detection of platelet isoantibodies is described. Gel filtration of the incubation mixture was incorporated in the procedure and proved effective for the removal of serum proteins from the platelet suspension. With this technique isoantibodies were found in the serum of 13 out of a group of 16 patients who had received multiple transfusions. The results were checked by measuring the uptake of 125I-labeled anti-IgG fraction by gel-filtered platelets. Subsequently the membrane immunofluorescence method was also compared with established techniques described for the detection of isoantibodies such as the microtest for lymphocytotoxicity and a complement-fixation method and the procedures based on the release of labeled serotonin, the phagocytosis of chromium-tagged platelets, the increase of platelet factor 3 activity, and on platelet aggregation. We had the opportunity to investigate the serum of one patient for the presence of isoantibodies against platelets from HLA identical siblings both before and after the administration of their platelets. On the basis of this experience it is concluded that the membrane immunofluorescence test for platelet isoantibodies is a relatively simple method with a high degree of specificity and adequate sensitivity.

  14. Enhancement by platelets of oxygen radical responses of human neutrophils

    Energy Technology Data Exchange (ETDEWEB)

    McCulloch, K.K.; Powell, J.; Johnson, K.J.; Ward, P.A.

    1986-03-01

    When human blood neutrophils were incubated with immune complexes (consisting of IgG antibody) in the presence of platelets, there was a 2 to 10 fold enhancement in the generation of O-/sub 2/ and H/sub 2/O/sub 2/. This enhancement phenomenon was proportional to the dose of immune complex added and the number of platelets present. The response was not agonist specific since similar enhancement also occurred with the following agonists: phorbol myristate acetate, opsonized zymosan particles and the chemotactic peptide N-formyl-met-leu-phe. The platelet related phenomenon of enhanced O-/sub 2/ generation could not be reproduced by the addition of serotonin, histamine or platelet-derived growth factor and was not affected by prior treatment of platelets with cyclooxygenase inhibitors (indomethacin, piroxicam) or lipoxygenase inhibitors (nafazatrom, BW755C or nordihydroguaiaretic acid). However, activation of platelets by thrombin caused release into the platelet supernatant fluid of a factor that, only in the presence of immune complexes, caused enhanced O-/sub 2/ responses to neutrophils. These data indicate that platelets potentiate oxygen radical responses of human neutrophils and suggest a mechanisms by which platelets may participate in tissue injury which is mediated by oxygen radical products from activated neutrophils.

  15. Effects of Suilysin on Streptococcus suis-induced platelet aggregation

    Directory of Open Access Journals (Sweden)

    Shengwei Zhang

    2016-10-01

    Full Text Available Blood platelets play important roles during pathological thrombocytopenia in streptococcal toxic shock syndrome (STSS. Streptococcus suis (S. suis an emerging human pathogen, can cause STSS similarly to S. pyogenes. However, S. suis interactions with platelets are poorly understood. Here, we found that suilysin (SLY, different from other bacterial cholesterol-dependent cytolysins (CDCs, was the sole stimulus that induced platelet aggregation. Furthermore, the inside-out activation of GPIIb/IIIa of platelets mediated SLY-induced platelet aggregation. This process was triggered by Ca2+ influx that depend on the pore forming on platelets by SLY. Additionally, although SLY induced α-granule release occurred via the MLCK-dependent pathway, PLC-β-IP3/DAG-MLCK and Rho-ROCK-MLCK signaling were not involved in SLY-induced platelet aggregation. Interestingly, the pore dependent Ca2+ influx was also found to participate in the induction of platelet aggregation with pneumolysin (PLY and streptolysin O (SLO, two other CDCs. It is possible that the CDC-mediated platelet aggregation we observed in S. suis is a similar response mechanism to that used by a wide range of bacteria. These findings might lead to the discovery of potential therapeutic targets for S. suis-associated STSS.

  16. Effects of Suilysin on Streptococcus suis-Induced Platelet Aggregation

    Science.gov (United States)

    Zhang, Shengwei; Wang, Junping; Chen, Shaolong; Yin, Jiye; Pan, Zhiyuan; Liu, Keke; Li, Lin; Zheng, Yuling; Yuan, Yuan; Jiang, Yongqiang

    2016-01-01

    Blood platelets play important roles during pathological thrombocytopenia in streptococcal toxic shock syndrome (STSS). Streptococcus suis (S. suis) an emerging human pathogen, can cause STSS similarly to S. pyogenes. However, S. suis interactions with platelets are poorly understood. Here, we found that suilysin (SLY), different from other bacterial cholesterol-dependent cytolysins (CDCs), was the sole stimulus that induced platelet aggregation. Furthermore, the inside-out activation of GPIIb/IIIa of platelets mediated SLY-induced platelet aggregation. This process was triggered by Ca2+ influx that depend on the pore forming on platelets by SLY. Additionally, although SLY induced α-granule release occurred via the MLCK-dependent pathway, PLC-β-IP3/DAG-MLCK and Rho-ROCK-MLCK signaling were not involved in SLY-induced platelet aggregation. Interestingly, the pore dependent Ca2+ influx was also found to participate in the induction of platelet aggregation with pneumolysin (PLY) and streptolysin O (SLO), two other CDCs. It is possible that the CDC-mediated platelet aggregation we observed in S. suis is a similar response mechanism to that used by a wide range of bacteria. These findings might lead to the discovery of potential therapeutic targets for S. suis-associated STSS. PMID:27800304

  17. Bioactivity and stability of endogenous fibrogenic factors in platelet-rich fibrin

    DEFF Research Database (Denmark)

    Lundquist, R.; Dziegiel, M.H.; Agren, M.S.

    2008-01-01

    Platelet-rich fibrin (PRF) is an autologous fibrin sealant (FS) enriched with a platelet concentrate (> 1,000,000 platelets/microL) produced by the automated Vivostat system and used to enhance wound healing. The effects of PRF were compared with supernatant from thrombin-activated platelet...... concentrate, recombinant human platelet-derived growth factor (rhPDGF) isoforms, and a homologous FS in cultured normal human dermal fibroblasts. Also, the release of selected endogenous growth factors from PRF and their stability against proteolytic degradation were studied. The proliferative effect of PRF...... exceeded that of FS and rhPDGF-BB, although it was lower than thrombin-activated platelet concentrate possibly due to sustained growth factor release from platelets in PRF. Anti-PDGF antibody blocked the mitogenic effect of rhPDGF-BB but not that of PRF in growth-arrested fibroblasts. PRF promoted...

  18. Bioactivity and stability of endogenous fibrogenic factors in platelet-rich fibrin

    DEFF Research Database (Denmark)

    Lundquist, Rasmus; Dziegiel, Morten H; Agren, Magnus S

    2008-01-01

    Platelet-rich fibrin (PRF) is an autologous fibrin sealant (FS) enriched with a platelet concentrate (> 1,000,000 platelets/microL) produced by the automated Vivostat system and used to enhance wound healing. The effects of PRF were compared with supernatant from thrombin-activated platelet...... concentrate, recombinant human platelet-derived growth factor (rhPDGF) isoforms, and a homologous FS in cultured normal human dermal fibroblasts. Also, the release of selected endogenous growth factors from PRF and their stability against proteolytic degradation were studied. The proliferative effect of PRF...... exceeded that of FS and rhPDGF-BB, although it was lower than thrombin-activated platelet concentrate possibly due to sustained growth factor release from platelets in PRF. Anti-PDGF antibody blocked the mitogenic effect of rhPDGF-BB but not that of PRF in growth-arrested fibroblasts. PRF promoted...

  19. Analysis of release kinetics of growth factors in porcine platelet-rich plasma lyophilized powder%猪富血小板血浆冻干粉细胞因子释放的研究

    Institute of Scientific and Technical Information of China (English)

    潘龙; 徐剑炜

    2016-01-01

    Objective On the basis of acquiring enough porcine platelet rich plasma (PRP) with high concentration of platelets,we further seek an appropriate way to preserve PRP by lyophilization and explored the kinetics of growth factors released by PRP lyophilized powder.Methods Four experimental groups were arranged as following:(1) Fresh porcine PRP,(2) Group of PRP activated by calcium chloride (CaCl2) (Ca PRP),(3) Activated PRP followed by freeze drying (Ca-FD PRP),and (4) Freeze-dried PRP activated by CaCl2(FD-Ca PRP).All FD PRP samples were kept for 4 weeks at room temperature (22 ℃C).Concentrations of transforming growth factor-β1 (TGF-β1),platelet-derived growth factor-AB (PDGF-AB),and vascular endothelial growth factor (VEGF) were determined at time points of 15 min and 1 h respectively.Results Concentration of all growth factors in Ca PRP at 1 h were significantly higher than that in the PRP at same time point (P < 0.05).There was no statistical significance in variance of PDGF-AB concentrations between FD-Ca PRP [15 min:(6 137.5 ± 800.3) ng/L;1 h:(5 659.1± 656.4) ng/L] and Ca PRP [15 min:(5629.8± 580.1) ng/L;1 h:(5294.6±679.2) ng/L,P > 0.05].Levels of VEGF between Ca-FD PRP [15 min:(942.6 ± 178.5) ng/L;1 h:(895.8± 110.0) ng/L] and Ca PRP [15 min:(589.7± 272.9) ng/L;1 h:(782.5±109.5) ng/L] was not significantly different (P>0.05).However,TGF-β1 concentration in Ca-FDPRP[(14 801.5 ±445.2) ng/L] at 15 min was higher than that in Ca PRP [(7 812.6 ±571.0) ng/L,P < 0.05].Conclusion PRP can be activated efficiently by calcium chloride.Lyophilized PRP is still rich in growth factors after four weeks' preservation at room temperature,which reveals easy-to-use performance and wide possibility for clinical applications.%目的 在制备较高血小板浓度的猪富血小板血浆(PRP)基础上,探索PRP冷冻干燥(FD)方法,研究PRP冻干粉中细胞因子释放动力学.方法 实验分组:静置PRP组、PRP钙剂激活组(Ca PRP

  20. Challenges and promises for the development of donor-independent platelet transfusions.

    Science.gov (United States)

    Lambert, Michele P; Sullivan, Spencer K; Fuentes, Rudy; French, Deborah L; Poncz, Mortimer

    2013-04-25

    Platelet transfusions are often a life-saving intervention, and the use of platelet transfusions has been increasing. Donor-derived platelet availability can be challenging. Compounding this concern are additional limitations of donor-derived platelets, including variability in product unit quality and quantity, limited shelf life and the risks of product bacterial contamination, other transfusion-transmitted infections, and immunologic reactions. Because of these issues, there has been an effort to develop strategies to generate platelets from exogenously generated precursor cells. If successful, such platelets have the potential to be a safer, more consistent platelet product, while reducing the necessity for human donations. Moreover, ex vivo-generated autologous platelets or precursors may be beneficial for patients who are refractory to allogeneic platelets. For patients with inherited platelet disorders, ex vivo-generated platelets offer the promise of a treatment via the generation of autologous gene-corrected platelets. Theoretically, ex vivo-generated platelets also offer targeted delivery of ectopic proteins to sites of vascular injury. This review summarizes the current, state-of-the-art methodologies in delivering a clinically relevant ex vivo-derived platelet product, and it discusses significant challenges that must be overcome for this approach to become a clinical reality.

  1. PPARγ ligands decrease hydrostatic pressure-induced platelet aggregation and proinflammatory activity.

    Directory of Open Access Journals (Sweden)

    Fang Rao

    Full Text Available Hypertension is known to be associated with platelet overactivity, but the direct effects of hydrostatic pressure on platelet function remain unclear. The present study sought to investigate whether elevated hydrostatic pressure is responsible for platelet activation and to address the potential role of peroxisome proliferator-activated receptor-γ (PPARγ. We observed that hypertensive patients had significantly higher platelet volume and rate of ADP-induced platelets aggregation compared to the controls. In vitro, Primary human platelets were cultured under standard (0 mmHg or increased (120, 180, 240 mmHg hydrostatic pressure for 18 h. Exposure to elevated pressure was associated with morphological changes in platelets. Platelet aggregation and PAC-1 (the active confirmation of GPIIb/IIIa binding were increased, CD40L was translocated from cytoplasm to the surface of platelet and soluble CD40L (sCD40L was released into the medium in response to elevated hydrostatic pressure (180 and 240 mmHg. The PPARγ activity was up-regulated as the pressure was increased from 120 mmHg to 180 mmHg. Pressure-induced platelet aggregation, PAC-1 binding, and translocation and release of CD40L were all attenuated by the PPARγ agonist Thiazolidinediones (TZDs. These results demonstrate that platelet activation and aggregation are increased by exposure to elevated pressure and that PPARγ may modulate platelet activation induced by high hydrostatic pressure.

  2. The PPAR-Platelet Connection: Modulators of Inflammation and Potential Cardiovascular Effects.

    Science.gov (United States)

    Spinelli, S L; O'Brien, J J; Bancos, S; Lehmann, G M; Springer, D L; Blumberg, N; Francis, C W; Taubman, M B; Phipps, R P

    2008-01-01

    Historically, platelets were viewed as simple anucleate cells responsible for initiating thrombosis and maintaining hemostasis, but clearly they are also key mediators of inflammation and immune cell activation. An emerging body of evidence links platelet function and thrombosis to vascular inflammation. peroxisome proliferator-activated receptors (PPARs) play a major role in modulating inflammation and, interestingly, PPARs (PPARbeta/delta and PPARgamma) were recently identified in platelets. Additionally, PPAR agonists attenuate platelet activation; an important discovery for two reasons. First, activated platelets are formidable antagonists that initiate and prolong a cascade of events that contribute to cardiovascular disease (CVD) progression. Dampening platelet release of proinflammatory mediators, including CD40 ligand (CD40L, CD154), is essential to hinder this cascade. Second, understanding the biologic importance of platelet PPARs and the mechanism(s) by which PPARs regulate platelet activation will be imperative in designing therapeutic strategies lacking the deleterious or unwanted side effects of current treatment options.

  3. Role of platelets in the pathogenesis of antiphospholipid syndrome

    Directory of Open Access Journals (Sweden)

    NK Singh

    2013-07-01

    Full Text Available AimTo delineate the role of platelets in thrombotic process in APS patients.BackgroundPathogenesis of APS is an ongoing area of research and studying the role of platelets will be helpful in developing newer diagnostic and therapeutic strategies.Materials and methodsForty patients with APS, diagnosed as per modified 2006 Sapporo’s Criteria and who were not on aspirin or any other antiplatelet drug, were included. The same number of age- and sex-matched healthy controls was also recruited for comparison. The following platelet function studies were performed using the blood samples collected from APS patients as well as healthy controls: platelet aggregation studies, platelet secretion of dense granules (a. total degranulation b. platelet secretion of granules in relation to time c. visualization of platelet degranulation, clot retraction studies, and western blot studies on clot retracted samples for demonstration of activated proteomes.ResultsA significant increase (P < 0.001 in the platelet aggregation in APS patients as compared to healthy controls was noted. The subjects also showed a significant increase (P < 0.05 in the platelet granule release as well as more degranulation (P < 0.001 in relation to time at stored condition, which were well-visualized under phase-contrast microscope. Sixty-five percent of APS patients showed lesser as well as delayed clot retraction as compared to healthy controls, signifying that the platelet clots are less retractile in APS patients.ConclusionThe study clearly demonstrates the hyperactivity of platelets in APS patients in each step of their activation as compared to the controls. This indicates the major role played by platelets in APS pathogenesis.

  4. Platelet alloimmunization after transfusion

    DEFF Research Database (Denmark)

    Taaning, E; Simonsen, A C; Hjelms, E;

    1997-01-01

    BACKGROUND AND OBJECTIVES: The frequency of platelet-specific antibodies after one series of blood transfusions has not been reported, and in multiply transfused patients is controversial. MATERIALS AND METHODS: We studied the frequency of alloimmunization against platelet antigens in 117 patient...

  5. Flavanols and Platelet Reactivity

    Directory of Open Access Journals (Sweden)

    Debra A. Pearson

    2005-01-01

    Full Text Available Platelet activity and platelet-endothelial cell interactions are important in the acute development of thrombosis, as well as in the pathogenesis of cardiovascular disease. An increasing number of foods have been reported to have platelet-inhibitory actions, and research with a number of flavanol-rich foods, including, grape juice, cocoa and chocolate, suggests that these foods may provide some protection against thrombosis. In the present report, we review a series of in vivo studies on the effects of flavanol-rich cocoa and chocolate on platelet activation and platelet-dependent primary hemostasis. Consumption of flavanol-rich cocoa inhibited several measures of platelet activity including, epinephrine- and ADP-induced glycoprotein (GP IIb/IIIa and P-Selectin expression, platelet microparticle formation, and epinephrine-collagen and ADP-collagen induced primary hemostasis. The epinephrine-induced inhibitory effects on GP IIb/IIIa and primary hemostasis were similar to, though less robust than those associated with the use of low dose (81 mg aspirin. These data, coupled with information from other studies, support the concept that flavanols present in cocoa and chocolate can modulate platelet function through a multitude of pathways.

  6. Platelet activation and aggregation

    DEFF Research Database (Denmark)

    Jensen, Maria Sander; Larsen, O H; Christiansen, Kirsten

    2013-01-01

    This study introduces a new laboratory model of whole blood platelet aggregation stimulated by endogenously generated thrombin, and explores this aspect in haemophilia A in which impaired thrombin generation is a major hallmark. The method was established to measure platelet aggregation initiated...

  7. Gasotransmitters and platelets.

    Science.gov (United States)

    Truss, Nicola J; Warner, Timothy D

    2011-11-01

    Platelets are essential to prevent blood loss and promote wound healing. Their activation comprises of several complex steps which are regulated by a range of mediators. Over the last few decades there has been intense interest in a group of gaseous mediators known as gasotransmitters; currently comprising nitric oxide (NO), carbon monoxide (CO) and hydrogen sulphide (H(2)S). Here we consider the action of gasotransmitters on platelet activity. NO is a well established platelet inhibitor which mediates its effects predominantly through activation of soluble guanylyl cyclase leading to a decrease in intraplatelet calcium. More recently CO has been identified as a gasotransmitter with inhibitory actions on platelets; CO acts through the same mechanism as NO but is less potent. The in vivo and platelet functions of the most recently identified gasotransmitter, H(2)S, are still the subject of investigations, but they appear generally inhibitory. Whilst there is evidence for the individual action of these mediators, it is also likely that combinations of these mediators are more relevant regulators of platelets. Furthermore, current evidence suggests that these mediators in combination alter the production of each other, and so modify the circulating levels of gasotransmitters. The use of gasotransmitters as therapeutic agents is also being explored for a range of indications. In conclusion, the importance of NO in the regulation of vascular tone and platelet activity has long been understood. Other gasotransmitters are now establishing themselves as mediators of vascular tone, and recent evidence suggests that these other gasotransmitters may also modulate platelet function.

  8. Alloimmune refractoriness to platelet transfusions.

    Science.gov (United States)

    Sandler, S G

    1997-11-01

    Patients who are transfused on multiple occasions with red cells or platelets may develop platelet-reactive alloantibodies and experience decreased clinical responsiveness to platelet transfusion. This situation, conventionally described as "refractoriness to platelet transfusions," is defined by an unsatisfactory low post-transfusion platelet count increment. If antibodies to HLAs are detected, improved clinical outcomes may result from transfusions of HLA-matched or donor-recipient cross-matched platelets. Because refractoriness is an expected, frequently occurring phenomenon, prevention of HLA alloimmunization is an important management strategy. Prevention strategies include efforts to decrease the number of transfusions, filtration of cellular components to reduce the number of HLA-bearing leukocytes, or pretransfusion ultraviolet B irradiation of cellular components to decrease their immunogenicity. Other investigational approaches include reducing the expression of HLAs on transfused platelets, inducing a transient reticuloendothelial system blockade by infusions of specialized immunoglobulin products, or transfusing semisynthetic platelet substitutes (thromboerythrocytes, thrombospheres) or modified platelets (infusible platelet membranes, lyophilized platelets).

  9. Platelet function in dogs

    DEFF Research Database (Denmark)

    Nielsen, Line A.; Zois, Nora Elisabeth; Pedersen, Henrik D.

    2007-01-01

    Cairn Terriers, 10 Boxers, and 11 Labrador Retrievers) were included in the study. Platelet function was assessed by whole-blood aggregation with ADP (1, 5, 10, and 20 µM) as agonist and by PFA-100 using collagen and epinephrine (Col + Epi) and Cpæ + ADP as agonists. Plasma thromboxane B2 concentration......Background: Clinical studies investigating platelet function in dogs have had conflicting results that may be caused by normal physiologic variation in platelet response to agonists. Objectives: The objective of this study was to investigate platelet function in clinically healthy dogs of 4...... different breeds by whole-blood aggregometry and with a point-of-care platelet function analyzer (PFA-100), and to evaluate the effect of acetylsalicylic acid (ASA) administration on the results from both methods. Methods: Forty-five clinically healthy dogs (12 Cavalier King Charles Spaniels [CKCS], 12...

  10. Cisplatin triggers platelet activation.

    Science.gov (United States)

    Togna, G I; Togna, A R; Franconi, M; Caprino, L

    2000-09-01

    Clinical observations suggest that anticancer drugs could contribute to the thrombotic complications of malignancy in treated patients. Thrombotic microangiopathy, myocardial infarction, and cerebrovascular thrombotic events have been reported for cisplatin, a drug widely used in the treatment of many solid tumours. The aim of this study is to explore in vitro cisplatin effect on human platelet reactivity in order to define the potentially active role of platelets in the pathogenesis of cisplatin-induced thrombotic complications. Our results demonstrate that cisplatin increases human platelet reactivity (onset of platelet aggregation wave and thromboxane production) to non-aggregating concentrations of the agonists involving arachidonic acid metabolism. Direct or indirect activation of platelet phospholipase A(2) appears to be implicated. This finding contributes to a better understanding of the pathogenesis of thrombotic complications occurring during cisplatin-based chemotherapy.

  11. Platelet function in dogs

    DEFF Research Database (Denmark)

    Nielsen, Line A.; Zois, Nora Elisabeth; Pedersen, Henrik D.

    2007-01-01

    Background: Clinical studies investigating platelet function in dogs have had conflicting results that may be caused by normal physiologic variation in platelet response to agonists. Objectives: The objective of this study was to investigate platelet function in clinically healthy dogs of 4...... different breeds by whole-blood aggregometry and with a point-of-care platelet function analyzer (PFA-100), and to evaluate the effect of acetylsalicylic acid (ASA) administration on the results from both methods. Methods: Forty-five clinically healthy dogs (12 Cavalier King Charles Spaniels [CKCS], 12...... applied. However, the importance of these breed differences remains to be investigated. The PFA-100 method with Col + Epi as agonists, and ADP-induced platelet aggregation appear to be sensitive to ASA in dogs....

  12. Selective inhibition of the platelet phosphoinositide 3-kinase p110beta as promising new strategy for platelet protection during extracorporeal circulation.

    Science.gov (United States)

    Straub, Andreas; Wendel, Hans Peter; Dietz, Klaus; Schiebold, Daniela; Peter, Karlheinz; Schoenwaelder, Simone M; Ziemer, Gerhard

    2008-03-01

    Extracorporeal circulation (ECC) is used in cardiac surgery for cardiopulmonary bypass as well as in ventricular assist devices and for extracorporeal membrane oxygenation. Blood contact with the artificial surface and shear stress of ECC activates platelets and leukocytes resulting in a coagulopathy and proinflammatory events. Blockers of the platelet glycoprotein (GP) IIb/IIIa (CD41/CD61) can protect platelet function during ECC, a phenomenon called "platelet anaesthesia", but may be involved in post-ECC bleeding. We hypothesized that the new selective phosphoinositide 3-kinase p110beta inhibitor TGX-221 that inhibits shear-induced platelet activation without prolonging the bleeding time in vivo may also protect platelet function during ECC. Heparinized blood of healthy volunteers (n = 6) was treated in vitro with either the GP IIb/IIIa blocker tirofiban, TGX-221 or as control and circulated in an ECC model. Before and after 30 minutes circulation CD41 expression on the ECC-tubing as measure for platelet-ECC binding and generation of the platelet activation marker beta-thromboglobulin were determined using ELISA. Platelet aggregation and platelet-granulocyte binding were analysed in flow cytometry. After log-transforming the data statistical evaluation was performed using multifactor ANOVA in combination with Tukey's HSD test (global alpha = 5%). Tirofiban and TGX-221 inhibited platelet-ECC interaction, platelet aggregation and platelet-granulocyte binding. Tirofiban also inhibited ECC-induced beta-thromboglobulin release. The observed inhibition of platelet-ECC interaction and platelet activation by tirofiban contributes to explain the mechanism of "platelet anaesthesia". TGX-221 represents a promising alternative to GP IIb/IIIa blockade and should be further investigated for use during ECC in vivo.

  13. Clinical Analysis of Ibuprofen Sustained-Release Capsules Adverse Reaction%布洛芬缓释胶囊不良反应的临床分析

    Institute of Scientific and Technical Information of China (English)

    陈忠琼

    2015-01-01

    Objective To investigate the clinical adverse reactions Ibuprofen Sustained-Release Capsules happened.Methods 42 cases of adverse reactions induced by Ibuprofen Sustained-Release Capsules were colected from 2010 December to 2014 June in our hospital were reported,and their clinical data were retrospectively analyzed.Results Adverse reactions Ibuprofen Sustained-Release Capsules to indigestion,frequent micturition, make water is painful and rash mainly;time to 3~5 d and 10 d more than the main occurrence;and under the age of 30 and 31~39 years old patients,the incidence of male cases were significantly higher than that in female;and women over 60 years of age incidence significantly higher than male patients,the difference was statisticaly significant(P<0.05).Conclusion Bloven sustained release capsules adverse reactions occurred mainly in the intestine and alergic reactions is given priority to,understand the characteristics of the adverse reactions of the rational use of the drugs for.%目的:探讨布洛芬缓释胶囊发生的临床不良反应。方法收集2010年12月至2014年6月我院报告的布洛芬缓释胶囊致不良反应42例,对其进行回顾性分析。结果布洛芬缓释胶囊的不良反应以消化不良、尿频、尿痛及单纯皮疹为主;发生时间以3~5 d及10 d以上为主;且30岁以下及31~39岁的患者中,男性发病例数均明显高于女性;而女性60岁以上发病例数明显高于男性,差异均有统计学意义(均P<0.05)。结论布洛芬缓释胶囊发生不良反应主要以肠道及过敏反应为主,了解其不良反应特点有利于临床的合理使用。

  14. Platelet function and fibrinolytic activity following distance running.

    Science.gov (United States)

    Knudsen, J B; Brodthagen, U; Gormsen, J; Jordal, R; Nørregaard-Hansen, K; Paulev, P E

    1982-11-01

    6 long distance runners from the Danish marathon elite and 6 non-runners completed test runs of 28 and 12 km, respectively. Distance runners and non-runners showed the same responses in platelet function. We found a significant decrease in ADP induced platelet aggregability, a decreased serotonin release induced by ADP and collagen and an increase in platelet factor 4 immediately following the run. The antithrombin III levels remained constant. Euglobulin lysis time was shortened (by approximately 50%) and the plasminogen levels significantly increased. The last 2 findings indicate an equal increase in fibrinolytic activity during distance running in both groups. While short term, strenuous exercise induces platelet hyperaggregation, long term distance running induces a state of exhaustion of platelet aggregation capacity.

  15. Measurement of platelet aggregation, independently of patient platelet count

    DEFF Research Database (Denmark)

    Vinholt, P. J.; Frederiksen, H.; Hvas, A.M.

    2017-01-01

    platelet aggregation ruled out bleeding tendency in thrombocytopenic patients. Summary: Background: Methods for testing platelet aggregation in thrombocytopenia are lacking. Objective: To establish a flow-cytometric test of in vitro platelet aggregation independently of the patient's platelet count......, and examine the association of aggregation with a bleeding history in thrombocytopenic patients. Patients/methods: We established a flow-cytometric assay of platelet aggregation, and measured samples from healthy individuals preincubated with antiplatelet drugs, and samples from two patients with inherited...... platelets at platelet counts of > 10 × 109 L-1; otherwise, platelet isolation was required. The platelet aggregation percentage decreased with increasing antiplatelet drug concentration. Platelet aggregation in patients was reduced as compared with healthy individuals: 42% (interquartile range [IQR] 27...

  16. The Signaling Role of CD40 Ligand in Platelet Biology and in Platelet Component Transfusion

    Directory of Open Access Journals (Sweden)

    Chaker Aoui

    2014-12-01

    Full Text Available The CD40 ligand (CD40L is a transmembrane molecule of crucial interest in cell signaling in innate and adaptive immunity. It is expressed by a variety of cells, but mainly by activated T-lymphocytes and platelets. CD40L may be cleaved into a soluble form (sCD40L that has a cytokine-like activity. Both forms bind to several receptors, including CD40. This interaction is necessary for the antigen specific immune response. Furthermore, CD40L and sCD40L are involved in inflammation and a panoply of immune related and vascular pathologies. Soluble CD40L is primarily produced by platelets after activation, degranulation and cleavage, which may present a problem for transfusion. Soluble CD40L is involved in adverse transfusion events including transfusion related acute lung injury (TRALI. Although platelet storage designed for transfusion occurs in sterile conditions, platelets are activated and release sCD40L without known agonists. Recently, proteomic studies identified signaling pathways activated in platelet concentrates. Soluble CD40L is a good candidate for platelet activation in an auto-amplification loop. In this review, we describe the immunomodulatory role of CD40L in physiological and pathological conditions. We will focus on the main signaling pathways activated by CD40L after binding to its different receptors.

  17. Measurement Uncertainty of Chromogenic LAL Assays: Reaction Time and Proportion of Endotoxin and LAL Reagent Affect Release of p-Nitroaniline.

    Science.gov (United States)

    Ostronoff, Celina Silva; Lourenço, Felipe Rebello

    2015-01-01

    Limulus Amebocyte Lysate (LAL) assays are widely used for detection and quantification of bacterial endotoxins in pharmaceuticals and medical devices. However, there are only a few studies on the measurement uncertainty of LAL assays. The aim of this work was to identify and quantify the main sources of measurement uncertainty for end point and kinetic-chromogenic LAL assays. Response surface methodology was used to study how the release of p-nitroaniline (pNA) is affected by reaction time and proportion of endotoxin and LAL reagent in end point and kinetic-chromogenic LAL assays, respectively. Increased release of pNA was observed when reaction time was increased. In addition, if different volumes of sample (or endotoxin standard) and LAL reagent are used, the pNA release rate will be affected. These results may be due to the increased interaction between the bacterial endotoxin and LAL-activated enzyme. Final measurement uncertainties (95% confidence interval) were 90-120% and 90-127% of bacterial endotoxin content for end point and kinetic-chromogenic assays, respectively. These values are reasonable for the scope of the method and allow the application of these measurement uncertainties in routine analysis of pharmaceuticals and medical devices.

  18. In vivo evaluation of copper release and acute local tissue reactions after implantation of copper-coated titanium implants in rats.

    Science.gov (United States)

    Hoene, Andreas; Prinz, Cornelia; Walschus, Uwe; Lucke, Silke; Patrzyk, Maciej; Wilhelm, Lutz; Neumann, Hans-Georg; Schlosser, Michael

    2013-06-01

    Copper (Cu) based coatings can reduce infections for titanium (Ti) implants. However, Cu is also cytotoxic. To examine the balance of antibacterial versus adverse tissue effects, this study aimed at evaluating a Cu coating regarding in vivo Cu release and local inflammatory reactions for 72 h. TiAl6V4 plates received either plasma electrolytic oxidation only (Ti), or an additional galvanic Cu deposition (Ti-Cu). No Staphylococcus aureus were found in vitro on Ti-Cu after 24 h. Following simultaneous intramuscular implantation of two Ti and two Ti-Cu plates into nine rats, serum Cu was elevated until 48 h and residual Cu on explanted samples reduced accordingly after 48 h. Total and tissue macrophages around implants increased until 72 h for both series, and were increased for Ti-Cu. As numbers of total and tissue macrophages were comparable, macrophages were probably tissue-derived. MHC-class-II-positive cells increased for Ti-Cu only. T-lymphocytes had considerably lower numbers than macrophages, did not increase or differ between both series, and thus had minor importance. Tissue reactions increased beyond Cu release, indicating effects of either surface-bound Cu or more likely the implants themselves. Altogether, Ti-Cu samples possessed antibacterial effectiveness in vitro, released measurable Cu amounts in vivo and caused a moderately increased local inflammatory response, demonstrating anti-infective potential of Cu coatings.

  19. Physical and functional association of the Src family kinases Fyn and Lyn with the collagen receptor glycoprotein VI-Fc receptor gamma chain complex on human platelets.

    Science.gov (United States)

    Ezumi, Y; Shindoh, K; Tsuji, M; Takayama, H

    1998-07-20

    We have previously shown that uncharacterized glycoprotein VI (GPVI), which is constitutively associated and coexpressed with Fc receptor gamma chain (FcRgamma) in human platelets, is essential for collagen-stimulated tyrosine phosphorylation of FcRgamma, Syk, and phospholipase Cgamma2 (PLCgamma2), leading to platelet activation. Here we investigated involvement of the Src family in the proximal signals through the GPVI-FcRgamma complex, using the snake venom convulxin from Crotalus durissus terrificus, which specifically recognizes GPVI and activates platelets through cross-linking GPVI. Convulxin-coupled beads precipitated the GPVI-FcRgamma complex from platelet lysates. Collagen and convulxin induced tyrosine phosphorylation of FcRgamma, Syk, and PLCgamma2 and recruited tyrosine-phosphorylated Syk to the GPVI-FcRgamma complex. Using coprecipitation methods with convulxin-coupled beads and antibodies against FcRgamma and the Src family, we showed that Fyn and Lyn, but not Yes, Src, Fgr, Hck, and Lck, were physically associated with the GPVI-FcRgamma complex irrespective of stimulation. Furthermore, Fyn was rapidly activated by collagen or cross-linking GPVI. The Src family-specific inhibitor PP1 dose-dependently inhibited collagen- or convulxin-induced tyrosine phosphorylation of proteins including FcRgamma, Syk, and PLCgamma2, accompanied by a loss of aggregation and ATP release reaction. These results indicate that the Src family plays a critical role in platelet activation via the collagen receptor GPVI-FcRgamma complex.

  20. Physical and Functional Association of the Src Family Kinases Fyn and Lyn with the Collagen Receptor Glycoprotein VI-Fc Receptor γ Chain Complex on Human Platelets

    Science.gov (United States)

    Ezumi, Yasuharu; Shindoh, Keisuke; Tsuji, Masaaki; Takayama, Hiroshi

    1998-01-01

    We have previously shown that uncharacterized glycoprotein VI (GPVI), which is constitutively associated and coexpressed with Fc receptor γ chain (FcRγ) in human platelets, is essential for collagen-stimulated tyrosine phosphorylation of FcRγ, Syk, and phospholipase Cγ2 (PLCγ2), leading to platelet activation. Here we investigated involvement of the Src family in the proximal signals through the GPVI–FcRγ complex, using the snake venom convulxin from Crotalus durissus terrificus, which specifically recognizes GPVI and activates platelets through cross-linking GPVI. Convulxin-coupled beads precipitated the GPVI–FcRγ complex from platelet lysates. Collagen and convulxin induced tyrosine phosphorylation of FcRγ, Syk, and PLCγ2 and recruited tyrosine-phosphorylated Syk to the GPVI–FcRγ complex. Using coprecipitation methods with convulxin-coupled beads and antibodies against FcRγ and the Src family, we showed that Fyn and Lyn, but not Yes, Src, Fgr, Hck, and Lck, were physically associated with the GPVI–FcRγ complex irrespective of stimulation. Furthermore, Fyn was rapidly activated by collagen or cross-linking GPVI. The Src family–specific inhibitor PP1 dose-dependently inhibited collagen- or convulxin-induced tyrosine phosphorylation of proteins including FcRγ, Syk, and PLCγ2, accompanied by a loss of aggregation and ATP release reaction. These results indicate that the Src family plays a critical role in platelet activation via the collagen receptor GPVI–FcRγ complex. PMID:9670039

  1. Defining Platelet Function During Polytrauma

    Science.gov (United States)

    2013-02-01

    using calibrated automated thrombography ( CAT ). 3. Platelet-induced clot contraction and using viscoelastic measures such as TEG with Platelet Mapping...using calibrated automated thrombography ( CAT ) in platelet-rich plasma. 3. Platelet-induced clot contraction and effect on clot structure by platelet...if injury with stable vital signs on initial evaluation.  Pregnancy (confirmed with urine pregnancy testing)  Documented do not resuscitate order

  2. Biochemical lesions of platelets stored as concentrates in PVC bags.

    Science.gov (United States)

    Krishnan, L K; Mathai, J; Sulochana, P V; Jacob, J; Sivakumar, R

    1997-02-01

    Acid-base status of platelet suspension during storage is a measure of the gas permeability of the bag material. To assess the efficacy of the bags available in our market to store platelets, we compared biochemical lesions of platelets stored in an Indian polyvinyl chloride (PVC) triple bag against a Japanese PVC bag standardized for 5 days platelet storage. Platelet concentrates prepared in both control and test PVC bags were stored for 72 h. Two ml samples were drawn 1 h after preparation, and then at 24 h intervals, for analysis. Our data show that the mean pH value in the test bags was maintained above 6.5. However, the CO2 tension was high and O2 tension was low. We also analyzed malondialdehyde (MDA) formation which is a measure of arachidonic acid metabolism, and seemed to be unaffected in stored platelets. Lactate dehydrogenase (LDH) was not released into the plasma excessively and hence significant platelet lysis was absent during storage. Hypotonic shock response (HSR) of platelets stored in both test and control bags was comparable, indicating the possibility of satisfactory post-transfusion recovery.

  3. Evaluation of an ethidium monoazide-enhanced 16S rDNA real-time polymerase chain reaction assay for bacterial screening of platelet concentrates and comparison with automated culture.

    Science.gov (United States)

    Garson, Jeremy A; Patel, Poorvi; McDonald, Carl; Ball, Joanne; Rosenberg, Gillian; Tettmar, Kate I; Brailsford, Susan R; Pitt, Tyrone; Tedder, Richard S

    2014-03-01

    Culture-based systems are currently the preferred means for bacterial screening of platelet (PLT) concentrates. Alternative bacterial detection techniques based on nucleic acid amplification have also been developed but these have yet to be fully evaluated. In this study we evaluate a novel 16S rDNA polymerase chain reaction (PCR) assay and compare its performance with automated culture. A total of 2050 time-expired, 176 fresh, and 400 initial-reactive PLT packs were tested by real-time PCR using broadly reactive 16S primers and a "universal" probe (TaqMan, Invitrogen). PLTs were also tested using a microbial detection system (BacT/ALERT, bioMérieux) under aerobic and anaerobic conditions. Seven of 2050 (0.34%) time-expired PLTs were found repeat reactive by PCR on the initial nucleic acid extract but none of these was confirmed positive on testing frozen second aliquots. BacT/ALERT testing also failed to confirm any time-expired PLTs positive on repeat testing, although 0.24% were reactive on the first test. Three of the 400 "initial-reactive" PLT packs were found by both PCR and BacT/ALERT to be contaminated (Escherichia coli, Listeria monocytogenes, and Streptococcus vestibularis identified) and 14 additional packs were confirmed positive by BacT/ALERT only. In 13 of these cases the contaminating organisms were identified as anaerobic skin or oral commensals and the remaining pack was contaminated with Streptococcus pneumoniae. These results demonstrate that the 16S PCR assay is less sensitive than BacT/ALERT and inappropriate for early testing of concentrates. However, rapid PCR assays such as this may be suitable for a strategy of late or prerelease testing. © 2013 American Association of Blood Banks.

  4. Platelet adhesion and degranulation induce pro-survival and pro-angiogenic signalling in ovarian cancer cells.

    Directory of Open Access Journals (Sweden)

    Karl Egan

    Full Text Available Thrombosis is common in ovarian cancer. However, the interaction of platelets with ovarian cancer cells has not been critically examined. To address this, we investigated platelet interactions in a range of ovarian cancer cell lines with different metastatic potentials [HIO-80, 59M, SK-OV-3, A2780, A2780cis]. Platelets adhered to ovarian cancer cells with the most significant adhesion to the 59M cell line. Ovarian cancer cells induced platelet activation [P-selectin expression] in a dose dependent manner, with the most significant activation seen in response to the 59M cell line. The platelet antagonists [cangrelor, MRS2179, and apyrase] inhibited 59M cell induced activation suggesting a P2Y12 and P2Y1 receptor mediated mechanism of platelet activation dependent on the release of ADP by 59M cells. A2780 and 59M cells potentiated PAR-1, PAR-4, and TxA2 receptor mediated platelet activation, but had no effect on ADP, epinephrine, or collagen induced activation. Analysis of gene expression changes in ovarian cancer cells following treatment with washed platelets or platelet releasate showed a subtle but valid upregulation of anti-apoptotic, anti-autophagy pro-angiogenic, pro-cell cycle and metabolic genes. Thus, ovarian cancer cells with different metastatic potential adhere and activate platelets differentially while both platelets and platelet releasate mediate pro-survival and pro-angiogenic signals in ovarian cancer cells.

  5. Platelet lysate as a substitute for animal serum for the ex-vivo expansion of mesenchymal stem/stromal cells: present and future.

    Science.gov (United States)

    Astori, Giuseppe; Amati, Eliana; Bambi, Franco; Bernardi, Martina; Chieregato, Katia; Schäfer, Richard; Sella, Sabrina; Rodeghiero, Francesco

    2016-07-13

    The use of fetal bovine serum (FBS) as a cell culture supplement is discouraged by regulatory authorities to limit the risk of zoonoses and xenogeneic immune reactions in the transplanted host. Additionally, FBS production came under scrutiny due to animal welfare concerns. Platelet derivatives have been proposed as FBS substitutes for the ex-vivo expansion of mesenchymal stem/stromal cells (MSCs) since platelet-derived growth factors can promote MSC ex-vivo expansion. Platelet-derived growth factors are present in platelet lysate (PL) obtained after repeated freezing-thawing cycles of the platelet-rich plasma or by applying physiological stimuli such as thrombin or CaCl2.PL-expanded MSCs have been used already in the clinic, taking advantage of their faster proliferation compared with FBS-expanded preparations. Should PL be applied to other biopharmaceutical products, its demand is likely to increase dramatically. The use of fresh platelet units for the production of PL raises concerns due to limited availability of platelet donors. Expired units might represent an alternative, but further data are needed to define safety, including pathogen reduction, and functionality of the obtained PL. In addition, relevant questions concerning the definition of PL release criteria, including concentration ranges of specific growth factors in PL batches for various clinical indications, also need to be addressed. We are still far from a common definition of PL and standardized PL manufacture due to our limited knowledge of the mechanisms that mediate PL-promoting cell growth. Here, we concisely discuss aspects of PL as MSC culture supplement as a preliminary step towards an agreed definition of the required characteristics of PL for the requirements of manufacturers and users.

  6. Beta-lactam antibiotic-mediated changes in platelet reactivity and vascular endothelial functions.

    Science.gov (United States)

    Togna, G I; Togna, A R; Caprino, L

    2001-05-01

    To evaluate vascular and platelet compatibility of intravenous administration of beta-lactam antibiotics, we assessed the effects of therapeutic concentrations of ceftriaxone, aztreonam, and ceftazidime on platelet reactivity to different agonists (sodium arachidonate, collagen and adenosine diphosphate) and on selected vascular endothelial functions (adenosine diphosphatase activity, prostacyclin production and t-PA release). Ceftriaxone and, to a lesser degree, aztreonam, enhanced platelet reactivity, evaluated as onset of platelet aggregating response, and increased thromboxane production to subthreshold concentrations of arachidonate. There was no modification in platelet reactivity after ceftazidime treatment. Ceftriaxone and ceftazidime, but not aztreonam, inhibited endothelial adenosine diphosphatase activity. Prostacyclin production and t-PA release were inhibited only by ceftriaxone at high concentrations. While it is difficult to establish which marker (platelet or endothelial functions) has more clinical reference in human vascular compatibility, it seems feasible to consider aztreonam the most compatible of the beta-lactams studied.

  7. Role of reactive nitrogen species in blood platelet functions.

    Science.gov (United States)

    Olas, Beata; Wachowicz, Barbara

    2007-12-01

    Blood platelets, in analogy to other circulating blood cells, can generate reactive oxygen/nitrogen species (ROS/RNS) that may behave as second messengers and may regulate platelet functions. Accumulating evidence suggest a role of ROS/RNS in platelet activation. On the other hand, an increased production of ROS/RNS causes oxidative stress, and thus, may contribute to the development of different diseases, including vascular complications, inflammatory and psychiatric illnesses. Oxidative stress in platelets leads to chemical changes in a wide range of their components, and platelet proteins may be initial targets of ROS/RNS action. It has been demonstrated that reaction of proteins with ROS/RNS results in the oxidation and nitration of some amino acid residues, formation of aggregates or fragmentation of proteins. In oxidized proteins new carbonyl groups and protein hydroperoxides are also formed. In platelets, low molecular weight thiols such as glutathione (GSH), cysteine and cysteinylglycine and protein thiols may be also target for ROS/RNS action. This review describes the chemical structure and biological activities of reactive nitrogen species, mainly nitric oxide ((*)NO) and peroxynitrite (ONOO(-)) and their effects on blood platelet functions, and the mechanisms involved in their action on platelets.

  8. Clinical application of radiolabelled platelets

    Energy Technology Data Exchange (ETDEWEB)

    Kessler, C. (Medical University Luebeck (Federal Republic of Germany). Department of Neurology); Hardeman, M.R. (Amsterdam Univ. (Netherlands). Academisch Ziekenhuis); Henningsen, H. (Heidelberg Univ. (Germany, F.R.). Neurologische Klinik); Petrovici, J.-N. (Cologne-Merheim Hospital (Federal Republic of Germany). Department of Neurology) (eds.)

    1990-01-01

    The increasing number of therapeutic modalities available for the management of patients with thromboembolic complications, such as fibrinolytic treatment or vascular surgery, require the development of new imaging techniques to provide more information on the xtent, age and activity of the thromboembolic material causing clinical symptoms. Since the introduction of radiolabelling of platelets with indium-111, platelet scintigraphy (PSC) has been used as a tool in the diagnosis of various thromboembolic diseases. During the International Symposium on Radiolabelled Platelets scientists from a variety of medical backgrounds presented their results on the clinical applictions of radiolabelled platelets. The papers presented there have been updated to take account of the latest results before publication in this volume. 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. refs.; figs.; tabs.

  9. 富血小板纤维蛋白与富血小板血浆体外释放生长因子的比较及其对脂肪干细胞增殖分化的影响%The comparison of platelet-rich fibrin and platelet-rich plasma in releasing of growth factors and their effects on the proliferation and differentiation of adipose tissue-derived stem cells in vitro

    Institute of Scientific and Technical Information of China (English)

    杨世茂; 王明国; 李静; 刘金盼; 林夏莲; 徐炜

    2012-01-01

    目的 比较富血小板纤维蛋白(PRF)与富血小板血浆(PRP)体外释放生长因子的质量浓度及其对脂肪干细胞(ADSCs)增殖和成骨分化的影响.方法 抽取兔耳中央动脉血,一次离心法制备PRF,二次离心法制备PRP,分别将其置于5 mL新鲜的α-MEM培养液中,分别于37℃下静置1、7、14、21、28 d,收集PRF与PRP析出液,检测析出液中转化生长因子-β1(TGF-β1)及血小板源性生长因子-AB(PDGF-AB)的质量浓度.将收集的PRF与PRP析出液配置成条件培养液培养ADSCs,观察其对ADSCs增殖及碱性磷酸酶(ALP)活性的影响.结果 1)生长因子释放情况:不同时间点的PRF析出液中,14d时TGF-β1的质量浓度达到最高,7d时PDGF-AB的质量浓度最高;不同时间点的PRP析出液中,1d时TGF-β1与PDGF-AB的质量浓度即达最高,以后逐渐下降.2)对ADSCs增殖及ALP活性的影响:PRF析出液中,14 d时对其影响最大;PRP析出液中,1d时对其影响最大.结论 与PRP相比,PRF能够缓慢持久地释放生长因子,更有力地刺激ADSCs的增殖和分化.%Objective To compare the releasing of growth factors between platelet-rich fibrin (PRF) and platelet-rich plasma (PRP) as well as their effects on the proliferation and differentiation of adipose tissue-derived stem cells (ADSCs) in vitro. Methods Blood was taken from central artery of rabbits, acquiring PRF was acquired through one time centrifuge and PRP through two times centrifuge. Five milliliters of fresh α-MEM was added to PRF and PRP and incubated at 37 ℃. The time points to collect exudates was in day 1, 7, 14, 21, 28 and the mass concentrations of transforming growth factor-β1 (TGF-β1) and platelet derived growth faetor-AB (PDGF-AB) were quantified in PRF and PRP. Then the exudates of PRF and PRP were used to culture ADSCs and evaluate the effects of PRF and PRP on proliferation and differentiation of ADSCs. Results 1) Growth factor release: In the PRF exudates at different time points

  10. Platelet preservation: agitation and containers.

    Science.gov (United States)

    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.

  11. Assessment of the influence of the inflammatory process on the activation of blood platelets and morphological parameters in patients with ulcerative colitis (colitis ulcerosa

    Directory of Open Access Journals (Sweden)

    Halina Kemona

    2011-04-01

    Full Text Available Ulcerative colitis (colitis ulcerosa is a non-specific inflammatory bowel disease of unknown etiology. The symptoms which are observed in the course of ulcerative colitis are: an increase in the number of leukocytes and blood platelets, an increase in the concentration of IL-6 and anemia. Blood platelets are the key element, linking the processes of hemostasis, inflammation and the repair of damaged tissues. Activation of blood platelets is connected with changes in their shape and the occurrence of the reaction of release. P-selectin appears on the surfaces of activated blood platelets and the concentration level of soluble P-selectin increases in the blood plasma. The aim of this study was to define whether the increased number of blood platelets in patients with ulcerative colitis accompanies changes in their activation and morphology. A total of 16 subjects with ulcerative colitis and 32 healthy subjects were studied. Mean platelet count, morphological parameters of platelets and MPC were measured using an ADVIA 120 hematology analyzer. Concentrations of sP-selectin and IL-6 in serum were marked by immunoassay (ELISA. MPC, concentration of sP-selectin and IL-6 were significantly higher in subjects with ulcerative colitis compared to those in the healthy group. There was a decrease of MPV in patients with ulcerative colitis, which is statistically significant. Chronic inflammation in patients with ulcerative colitis causes an increase in the number of blood platelets, a change in their morphology and activation. Decreased MPV value reflects activation and the role blood platelets play in the inflammatory process of the mucous membrane of the colon. A high concentration of sP-selectin, which is a marker of blood platelet activation, demonstrates their part in the inflammatory process. The increase in the concentration of sP-selectin correlated positively with the increase in concentration of IL-6. This is why it may be a useful marker

  12. Gray platelet syndrome and defective thrombo-inflammation in Nbeal2-deficient mice

    OpenAIRE

    Deppermann, Carsten; Cherpokova, Deya; Nurden, Paquita; Schulz, Jan-Niklas; Thielmann, Ina; Kraft, Peter; Vögtle, Timo; Kleinschnitz, Christoph; Dütting, Sebastian; Krohne, Georg; Eming, Sabine A.; Nurden, Alan T; Eckes, Beate; Stoll, Guido; Stegner, David

    2013-01-01

    Platelets are anuclear organelle-rich cell fragments derived from bone marrow megakaryocytes (MKs) that safeguard vascular integrity. The major platelet organelles, α-granules, release proteins that participate in thrombus formation and hemostasis. Proteins stored in α-granules are also thought to play a role in inflammation and wound healing, but their functional significance in vivo is unknown. Mutations in NBEAL2 have been linked to gray platelet syndrome (GPS), a rare bleeding disorder ch...

  13. Pistacia chinensis Methanolic Extract Attenuated MAPK and Akt Phosphorylations in ADP Stimulated Rat Platelets In Vitro

    Directory of Open Access Journals (Sweden)

    Ji Young Park

    2012-01-01

    (2.5–20 μg/mL inhibited ADP-induced platelet aggregation. While PCME diminished [Ca2+]i, ATP, and TXA2 release in ADP-activated platelets, it enhanced cAMP production in resting platelets. Likewise, PCME inhibited fibrinogen binding to αIIbβ3 and downregulated JNK, ERK, and Akt phosphorylations. Thus, PCME contains potential antiplatelet compounds that could be deployed for their therapeutic values in cardiovascular pathology.

  14. Effects of local application of platelet-rich plasma and guided tissue regeneration on stability of implants

    OpenAIRE

    Duka Miloš; Lazić Z.; Bubalo Marija; Tatić Z.; Đurđević D.; Matić Smiljana

    2010-01-01

    Osseointegration is a result of cellular migration, differentiation, bone formation, and bone remodelling on the surface of an implant. Each of these processes depends on platelets and blood coagulum. Platelet-rich plasma (PRP) is used to improve osseointegration and stability of implants. It is a blood fraction produced in a centrifuge which contains a high concentration of platelets. Platelets contain numerous growth factors which influence tissue reactions. The aim of the research is to te...

  15. Anatomy of the Lockerbie bombing: Libya’s role and reactions to al-Megrahi’s release.

    Directory of Open Access Journals (Sweden)

    K. J. Ani

    2015-04-01

    Full Text Available Despite its long historical antecedents, terrorism is amongst the growing realities of the national history of contemporary sovereign states. With this emergence, destabilizing influence, and internationalization, terrorism has made the associated security challenge a major diplomatic headache for all key international actors and diplomats. This paper, which adopts a theoretical approach, assesses claims that Ghadafi’s Libya championed state-sponsored terrorism. It reviews the Lockerbie bombing and the conviction of al-Megrahi by the court in Netherland as well as his release from Scottish prison on compassionate grounds. It examines Libya’s use of available diplomatic tools and channels not only to prevent Abdelbaset Ali Mohammed al-Megrahi from facing justice but also to attain Ghadafi’s political and economic interests. This article documents the political communication that followed his release and calls for increased diplomatic investigations of the Lockerbie terrorist attack. Finally, the paper beckons on Libya’s new leaders and the leaderships of USA and Scotland to engage in a progressive multilateral strategic cooperation to unravel further facts on the Lockerbie bombing while promoting the current international “war” against terrorism

  16. HMGB1 binds to activated platelets via the receptor for advanced glycation end products and is present in platelet rich human coronary artery thrombi.

    Science.gov (United States)

    Ahrens, Ingo; Chen, Yung-Chih; Topcic, Danijal; Bode, Michael; Haenel, David; Hagemeyer, Christoph E; Seeba, Hannah; Duerschmied, Daniel; Bassler, Nicole; Jandeleit-Dahm, Karin A; Sweet, Matthew J; Agrotis, Alex; Bobik, Alex; Peter, Karlheinz

    2015-11-01

    High mobility group box 1 (HMGB1) acts as both a nuclear protein that regulates gene expression, as well as a pro-inflammatory alarmin that is released from necrotic or activated cells. Recently, HMGB1-expression in human atherosclerotic plaques was identified. Therapeutic blockade of HMGB1 reduced the development of diet-induced atherosclerosis in ApoE knockout mice. Thus, we hypothesised an interaction between HMGB1 and activated platelets. Binding of recombinant HMGB1 to platelets was assessed by flow cytometry. HMGB1 bound to thrombin-activated human platelets (MFI 2.49 vs 25.01, p=0.0079). Blood from wild-type, TLR4 and RAGE knockout mice was used to determine potential HMGB1 receptors on platelets. HMGB1 bound to platelets from wild type C57Bl6 (MFI 2.64 vs 20.3, p 0.05). RAGE expression on human platelets was detected by RT-PCR with mRNA extracted from highly purified platelets and confirmed by Western blot and immunofluorescence microscopy. Platelet activation increased RAGE surface expression (MFI 4.85 vs 6.74, p< 0.05). Expression of HMGB1 in human coronary artery thrombi was demonstrated by immunohistochemistry and revealed high expression levels. Platelets bind HMGB1 upon thrombin-induced activation. Platelet specific expression of RAGE could be detected at the mRNA and protein level and is involved in the binding of HMGB1. Furthermore, platelet activation up-regulates platelet surface expression of RAGE. HMGB1 is highly expressed in platelet-rich human coronary artery thrombi pointing towards a central role for HMGB1 in atherothrombosis, thereby suggesting the possibility of platelet targeted anti-inflammatory therapies for atherothrombosis.

  17. Platelets mediate increased endothelium permeability in dengue through NLRP3-inflammasome activation.

    Science.gov (United States)

    Hottz, Eugenio D; Lopes, Juliana F; Freitas, Carla; Valls-de-Souza, Rogério; Oliveira, Marcus F; Bozza, Marcelo T; Da Poian, Andrea T; Weyrich, Andrew S; Zimmerman, Guy A; Bozza, Fernando A; Bozza, Patricia T

    2013-11-14

    Dengue is the most frequent hemorrhagic viral disease and re-emergent infection in the world. Although thrombocytopenia is characteristically observed in mild and severe forms of dengue, the role of platelet activation in dengue pathogenesis has not been fully elucidated. We hypothesize that platelets have major roles in inflammatory amplification and increased vascular permeability during severe forms of dengue. Here we investigate interleukin (IL)-1β synthesis, processing, and secretion in platelets during dengue virus (DV) infection and potential contribution of these events to endothelial permeability during infection. We observed increased expression of IL-1β in platelets and platelet-derived microparticles from patients with dengue or after platelet exposure to DV in vitro. We demonstrated that DV infection leads to assembly of nucleotide-binding domain leucine rich repeat containing protein (NLRP3) inflammasomes, activation of caspase-1, and caspase-1-dependent IL-1β secretion. Our findings also indicate that platelet-derived IL-1β is chiefly released in microparticles through mechanisms dependent on mitochondrial reactive oxygen species-triggered NLRP3 inflammasomes. Inflammasome activation and platelet shedding of IL-1β-rich microparticles correlated with signs of increased vascular permeability. Moreover, microparticles from DV-stimulated platelets induced enhanced permeability in vitro in an IL-1-dependent manner. Our findings provide new evidence that platelets contribute to increased vascular permeability in DV infection by inflammasome-dependent release of IL-1β.

  18. Collagen can selectively trigger a platelet secretory phenotype via glycoprotein VI.

    Directory of Open Access Journals (Sweden)

    Véronique Ollivier

    Full Text Available Platelets are not only central actors of hemostasis and thrombosis but also of other processes including inflammation, angiogenesis, and tissue regeneration. Accumulating evidence indicates that these "non classical" functions of platelets do not necessarily rely on their well-known ability to form thrombi upon activation. This suggests the existence of non-thrombotic alternative states of platelets activation. We investigated this possibility through dose-response analysis of thrombin- and collagen-induced changes in platelet phenotype, with regards to morphological and functional markers of platelet activation including shape change, aggregation, P-selectin and phosphatidylserine surface expression, integrin activation, and release of soluble factors. We show that collagen at low dose (0.25 µg/mL selectively triggers a platelet secretory phenotype characterized by the release of dense- and alpha granule-derived soluble factors without causing any of the other major platelet changes that usually accompany thrombus formation. Using a blocking antibody to glycoprotein VI (GPVI, we further show that this response is mediated by GPVI. Taken together, our results show that platelet activation goes beyond the mechanisms leading to platelet aggregation and also includes alternative platelet phenotypes that might contribute to their thrombus-independent functions.

  19. Platelet activation using electric pulse stimulation: growth factor profile and clinical implications.

    Science.gov (United States)

    Torres, Andrew S; Caiafa, Antonio; Garner, Allen L; Klopman, Steve; LaPlante, Nicole; Morton, Christine; Conway, Kenneth; Michelson, Alan D; Frelinger, Andrew L; Neculaes, V Bogdan

    2014-09-01

    Autologous platelet gel therapy using platelet-rich plasma has emerged as a promising alternative for chronic wound healing, hemostasis, and wound infection control. A critical step for this therapeutic approach is platelet activation, typically performed using bovine thrombin (BT) and calcium chloride. However, exposure of humans to BT can stimulate antibody formation, potentially resulting in severe hemorrhagic or thrombotic complications. Electric pulse stimulation using nanosecond PEFs (pulse electric fields) is an alternative, nonbiochemical platelet activation method, thereby avoiding exposure to xenogeneic thrombin and associated risks. In this study, we identified specific requirements for a clinically relevant activator instrument by dynamically measuring current, voltage, and electric impedance for platelet-rich plasma samples. From these samples, we investigated the profile of growth factors released from human platelets with electric pulse stimulation versus BT, specifically platelet-derived growth factor, transforming growth factor β, and epidermal growth factor, using commercial enzyme-linked immunosorbent assay kits. Electric pulse stimulation triggers growth factor release from platelet α-granules at the same or higher level compared with BT. Electric pulse stimulation is a fast, inexpensive, easy-to-use platelet activation method for autologous platelet gel therapy.

  20. Crocin prevents sesamol-induced oxidative stress and apoptosis in human platelets.

    Science.gov (United States)

    Thushara, Ram M; Hemshekhar, Mahadevappa; Paul, Manoj; Shanmuga Sundaram, Mahalingam; Shankar, Rohith L; Kemparaju, Kempaiah; Girish, Kesturu S

    2014-10-01

    Recent studies have reported the platelet proapoptotic propensity of plant-derived molecules such as, resveratrol, thymoquinone, andrographolide and gossypol. Meanwhile, there were also reports of phytochemicals such as cinnamtannin B1, which shows antiapoptotic effect towards platelets. Platelets are mainly involved in hemostasis, thrombosis and wound healing. However, altered platelet functions can have serious pathological outcomes that include cardiovascular diseases. Platelets are sensitive to external and internal stimuli including therapeutic and dietary components. The anuclear platelets do undergo apoptosis via mitochondrial pathway. However, exaggerated rate of platelet apoptosis could lead to thrombocytopenia and other bleeding disorders. The present study deals with ameliorative efficacy of crocin on sesamol-induced platelet apoptosis. The antiapoptotic property of crocin and the proapoptotic tendency of sesamol in platelets were previously demonstrated. Therefore, it was interesting to see how these two compounds would interact and wield their effects on human platelets. Crocin effectively inhibited sesamol-induced oxidative stress on platelets, which was evidenced by the measurement of endogenously generated reactive oxygen species, particularly hydrogen peroxide, and changes in thiol levels. Further, crocin abrogated sesamol-induced biochemical events of apoptosis in platelets, which include intracellular calcium mobilization, changes in mitochondrial membrane integrity, cytochrome c release, caspase activity and phosphatidylserine externalization. Even though sesamol has proapoptotic effects on platelets, its anti-platelet activity cannot be neglected. Thus, the study proposes that sesamol could be supplemented with crocin, an approach that could not only abolish the toxic effects of sesamol on platelets, but also enhance the quality of treatment due to their synergistic action.

  1. The Platelet and Platelet Function Testing in Liver Disease

    NARCIS (Netherlands)

    Hugenholtz, Greg G. C.; Porte, Robert J.; Lisman, Ton

    2009-01-01

    Patients who have liver disease commonly present with alterations in platelet number and function. Recent data have questioned the contribution of these changes to bleeding complications in these patients. Modern tests of platelet function revealed compensatory mechanisms for the decreased platelet

  2. Investigation of platelet function and platelet disorders using flow cytometry.

    Science.gov (United States)

    Rubak, Peter; Nissen, Peter H; Kristensen, Steen D; Hvas, Anne-Mette

    2016-01-01

    Patients with thrombocytopenia or platelet disorders are at risk of severe bleeding. We report the development and validation of flow cytometry assays to diagnose platelet disorders and to assess platelet function independently of platelet count. The assays were developed to measure glycoprotein levels (panel 1) and platelet function (panel 2) in sodium citrated blood. Twenty healthy volunteers and five patients diagnosed with different platelet disorders were included. Glycoprotein expression levels of the receptors Ia, Ib, IIb, IIIa and IX were measured and normalised with forward scatter (FS) as a measurement of platelet size. Platelet function was assessed by CD63, P-selectin and bound fibrinogen in response to arachidonic acid, adenosine diphosphate (ADP), collagen-related peptide, ristocetin and thrombin receptor-activation peptide-6. All patients except one with suspected δ-granule defect showed aberrant levels of glycoproteins in panel 1. Glanzmann's thrombasthenia and genetically verified Bernard-Soulier syndrome could be diagnosed using panel 1. All patients showed reduced platelet function according to at least one agonist. Using panel 2 it was possible to diagnose Bernard-Soulier syndrome, δ-granule defect and GPVI disorder. By combining the two assays, we were able to diagnose different platelet disorders and investigate platelet function independent of platelet count.

  3. Reproducibility of Manual Platelet Estimation Following Automated Low Platelet Counts

    Directory of Open Access Journals (Sweden)

    Zainab S Al-Hosni

    2016-11-01

    Full Text Available Objectives: Manual platelet estimation is one of the methods used when automated platelet estimates are very low. However, the reproducibility of manual platelet estimation has not been adequately studied. We sought to assess the reproducibility of manual platelet estimation following automated low platelet counts and to evaluate the impact of the level of experience of the person counting on the reproducibility of manual platelet estimates. Methods: In this cross-sectional study, peripheral blood films of patients with platelet counts less than 100 × 109/L were retrieved and given to four raters to perform manual platelet estimation independently using a predefined method (average of platelet counts in 10 fields using 100× objective multiplied by 20. Data were analyzed using intraclass correlation coefficient (ICC as a method of reproducibility assessment. Results: The ICC across the four raters was 0.840, indicating excellent agreement. The median difference of the two most experienced raters was 0 (range: -64 to 78. The level of platelet estimate by the least-experienced rater predicted the disagreement (p = 0.037. When assessing the difference between pairs of raters, there was no significant difference in the ICC (p = 0.420. Conclusions: The agreement between different raters using manual platelet estimation was excellent. Further confirmation is necessary, with a prospective study using a gold standard method of platelet counts.

  4. Injectable Mussel-Inspired Immobilization of Platelet-Rich Plasma on Microspheres Bridging Adipose Micro-Tissues to Improve Autologous Fat Transplantation by Controlling Release of PDGF and VEGF, Angiogenesis, Stem Cell Migration.

    Science.gov (United States)

    Zhou, Shaolong; Chang, Qiang; Lu, Feng; Xing, Malcolm

    2017-09-07

    Platelets-rich plasma (PRP) can produce growth factors (GFs) to improve angiogenesis. However, direct injection of PRP does not lead to highly localized GFs. The current study employs a mussel-inspired polydopamine to immobilize PRP on gelatin microspheres (GMs) with the purpose of bridging adipose micro-tissues to help implanted fat survive (GM-pDA-PRP). Enhanced PRP adhesion leads to a prolonged and localized production of GFs, which is verified by platelet counting and by ELISA of vascular endothelial growth factors (VEGFs) and of platelet derived growth factors (PDGFs). The GM-pDA-PRP "hatches" a microenvironment for the proliferation of adipose-derived stem cells. After the adipose micro-tissue has bridged with GM-pDA-PRP after 16 weeks, triple-fluorescence staining reveals that the mature adipocytes, blood vessels, and capillaries are arranged like in normal adipose tissue. The survival fat increases significantly compared to that in control, PRP, and GM-PRP groups (84.8 ± 11.4% versus 47.8 ± 8.9%, 56.9 ± 9.7%, and 60.2 ± 10.5%, respectively). Both histological assessments and CD31 immunofluorescence indicate that the improvement of angiogenesis in GM-pDA-PRP is higher than in the fat graft group (6.4-fold in quantitative CD31 positive cells). The CD34 positive cells in the GM-pDA-PRP group are around 3.5-fold the amount in the fat graft group, which suggests that more stem cells migrate to the implant area. Cell proliferation staining shows that the number of Ki67 positive cells is around five times as high as that in the fat graft group. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Exosomes: novel effectors of human platelet lysate activity

    Directory of Open Access Journals (Sweden)

    E Torreggiani

    2014-09-01

    Full Text Available 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.

  6. Duration of exposure to high fluid shear stress is critical in shear-induced platelet activation-aggregation.

    Science.gov (United States)

    Zhang, Jian-ning; Bergeron, Angela L; Yu, Qinghua; Sun, Carol; McBride, Latresha; Bray, Paul F; Dong, Jing-fei

    2003-10-01

    Platelet functions are increasingly measured under flow conditions to account for blood hydrodynamic effects. Typically, these studies involve exposing platelets to high shear stress for periods significantly longer than would occur in vivo. In the current study, we demonstrate that the platelet response to high shear depends on the duration of shear exposure. In response to a 100 dyn/cm2 shear stress for periods less than 10-20 sec, platelets in PRP or washed platelets were aggregated, but minimally activated as demonstrated by P-selectin expression and binding of the activation-dependent alphaIIbbeta3 antibody PAC-1 to sheared platelets. Furthermore, platelet aggregation under such short pulses of high shear was subjected to rapid disaggregation. The disaggregated platelets could be re-aggregated by ADP in a pattern similar to unsheared platelets. In comparison, platelets that are exposed to high shear for longer than 20 sec are activated and aggregated irreversibly. In contrast, platelet activation and aggregation were significantly greater in whole blood with significantly less disaggregation. The enhancement is likely via increased collision frequency of platelet-platelet interaction and duration of platelet-platelet association due to high cell density. It may also be attributed to the ADP release from other cells such as red blood cells because increased platelet aggregation in whole blood was partially inhibited by ADP blockage. These studies demonstrate that platelets have a higher threshold for shear stress than previously believed. In a pathologically relevant timeframe, high shear alone is likely to be insufficient in inducing platelet activation and aggregation, but acts synergistically with other stimuli.

  7. Interaction of platelets with poly(vinylidene fluoride-co-hexafluoropropylene) electrospun surfaces.

    Science.gov (United States)

    Ahmed, Furqan; Choudhury, Namita Roy; Dutta, Naba K; Brito e Abreu, Susana; Zannettino, Andrew; Duncan, Elizabeth

    2014-03-10

    Platelets are the major contributors in the process of thrombosis and in the failure of biomedical implants. A number of factors influence the platelet interaction with foreign surfaces such as surface morphology, surface chemistry, and adsorbed proteins. This study examined the effect of surface topography and chemistry of pristine and fibrinogen-adsorbed solvent cast (SC) and electrospun (ES) samples of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) on platelet adhesion, activation, and aggregation. Qualitative and quantitative studies of fibrinogen adsorption were performed using time-of-flight secondary ion mass spectrometry (ToF-SIMS), while SEM, aggregometry, and liquid scintillation analyses were performed to evaluate platelet adhesion, aggregation, and serotonin release. While little or no platelet adhesion was observed on pristine ES surfaces, considerable adhesion, and measurable aggregation and serotonin release were observed on pristine SC surfaces. Notably, increased adhesion of platelets was observed following fibrinogen adsorption on SC surface with considerable aggregation and serotonin release compared with ES samples, where limited aggregation and platelet adhesion was observed. A further comparison of platelet adhesion, aggregation, and serotonin release was performed with plasma-adsorbed SC and ES surfaces. SC surfaces showed enhanced platelet adhesion, aggregation, and serotonin release compared to ES surfaces. This study shows that the morphology of samples plays a critical role on the biocompatibility of samples by altering the adsorption and adhesion of biomolecules and cells. The low level of adhesion, low aggregation, and serotonin release of platelets, even in the presence of fibrinogen and plasma-derived proteins, suggested that ES samples have the least thrombogenicity.

  8. Platelet microbicidal activity is an important defense factor against viridans streptococcal endocarditis

    NARCIS (Netherlands)

    Krijgsveld, J; Joldersma, W; Zaat, SAJ; van der Werff, J.

    2001-01-01

    To study the role of platelet microbicidal activity in host defense against infective endocarditis (IE) due to viridans streptococci (VS), the susceptibility to platelet releasate of blood and oral VS isolates from patients with and without IE was compared. The influence of neutralization of platele

  9. Circulating levels of platelet α-granule cytokines in trauma patients

    DEFF Research Database (Denmark)

    Windeløv, Nis Agerlin; Ostrowski, Sisse Rye; Johansson, Per Ingemar

    2015-01-01

    OBJECTIVE AND DESIGN: To elucidate whether platelets differentiate cytokine release following trauma, we prospectively measured three major platelet-derived cytokines in 213 trauma patients on hospital arrival. METHODS: We measured plasma levels of the anti-inflammatory β-thromboglobulins (β...

  10. Studies of manufacturing controlled-release graphene acid and catalyzing synthesis of chalcone with Claisen-Schmidt condensation reaction

    Science.gov (United States)

    Li, Jihui; Feng, Jia; Li, Mei; Wang, Qiaolian; Su, Yumin; Jia, Zhixin

    2013-07-01

    In the paper, graphene acid (GA) was manufactured, using flake graphite as raw material, and the acidity and the structure of GA were characterized as well as. Then, chalcone was synthesized in the presence of GA, using acetophenone and benzaldehyde as the reactant. The results showed that the acidity of GA was for pH = 1.12 in aqueous solution, and it was structured by the graphene sheets with the spaces between the graphene sheet and the graphene sheet and sulfuric acid (H2SO4) and acetic acid (CH3CO2H) inside the spaces. At the same time, the results also exhibited that the chalcone yield was able to reach 60.36% when GA dosage was 5 g, and the chalcone yields could attain apart 60.36, 52.05 and 31.16% when 5 g of GA was used thrice. This shows that GA is not only a high-performance catalyst, but also a controlled-release catalyst.

  11. Correlation between the Female Apheresis Platelet Donors′ Sodium Citrate Toxic Reaction and the Anticoagulant Concentration%女性机采血小板献血者枸橼酸钠中毒与抗凝剂比例的关系

    Institute of Scientific and Technical Information of China (English)

    何晓露

    2012-01-01

    Objective To investigate the relationship of the female apheresis platelet donors' sodium citrate toxic reaction and the anticoagulant concentration. Methods 181 cases of female platelet donors at blood center were randomly divided into group A of 80 cases and group B. Of 101 cases, sodium citrate poisoning cases in anticoagulant/blood ratio of 1:10( group A)and 1: 11( group B )female platelet donors were observed and compared. Results When the ratio of anticoagulant and whole blood was 1=11,1.98% of the female donors of group B had sodium citrate toxicity reactions, which was significantly lower than group A with the ratio of anticoagulant and whole blood 1: 10. The difference of incidence of sodium toxic reactions was statistically significant( P <0. 05 ). Conclusion Women in Jiangsu Province generally have smaller body weight,the use of appropriate anticoagulant concentration( the ratio of anticoagulant and whole blood 1 : 11 )can significantly reduce the incidence of sodium citrate toxic reaction of the female apheresis platelet donors, which has important application value.%目的 探讨女性机采血小板献血者枸橼酸钠中毒与抗凝剂比例的关系.方法 对来血液中心进行机采血小板的181例女性献血者随机分为A组80例,B组101例.对比观察抗凝剂与全血比例为1:10(A组)和1:11时(B组)女性机采血小板献血者发生枸橼酸钠中毒的情况.结果 抗凝剂与全血比例为1:11的B组女性献血者枸橼酸钠中毒反应发生率为1.98%,明显低于抗凝剂与全血比例为1:10的A组女性献血者,比较差异有统计学意义(P<0.05).结论 江苏地区女性体质量普遍较轻,采用抗凝剂与全血比例为1:11可明显改善女性机采血小板献血者枸橼酸钠中毒反应的发生率,具有重要的应用价值.

  12. Desmopressin in inherited disorders of platelet function.

    Science.gov (United States)

    Coppola, A; Di Minno, G

    2008-01-01

    Following the first clinical use in haemophilia and von Willebrand disease in 1977, the synthetic analogue of vasopressin 1-deamino-8-D-arginine vasopressin (DDAVP, desmopressin) was successfully employed for the management of a series of bleeding disorders, including congenital and acquired defects of platelet function. In this setting, few haemostatic approaches are available and, in particular for severe bleeding and major invasive procedures, the transfusion of platelet concentrates is the first-choice treatment. Therefore, DDAVP was (and remains) an attractive therapeutic alternative, being well tolerated, cost-saving, administrable at home (by the intranasal or subcutaneous concentrated formulations) and, in particular, enabling the avoidance of blood product exposition and the related risks (allergic reactions, transfusion transmitted infections). Despite three decades of clinical use, cellular mechanisms of haemostatic effects of DDAVP in platelet defects remain poorly known and the excellent results reported in some case series have not been strengthened by rigorous clinical trials, hampered by the rarity and the heterogeneity of these disorders. However, clinical experience more than evidence-based medicine reserved an established place to DDAVP in the management of inherited platelet disorders. This review will focus the available clinical data and the open issues of DDAVP in this setting.

  13. Mean platelet volume and mean platelet volume/platelet count ratio ...

    African Journals Online (AJOL)

    Amira M. Elsayed

    2016-03-30

    Mar 30, 2016 ... Abstract The mean platelet volume (MPV) is a laboratory marker associated with platelet func- tion and activity. .... the first 24 h of presentation to the emergency department. Severity of ..... J Neurol Neurosurg Psychiatry.

  14. Sulfatides partition disabled-2 in response to platelet activation.

    Directory of Open Access Journals (Sweden)

    Karen E Drahos

    Full Text Available BACKGROUND: Platelets contact each other at the site of vascular injury to stop bleeding. One negative regulator of platelet aggregation is Disabled-2 (Dab2, which is released to the extracellular surface upon platelet activation. Dab2 inhibits platelet aggregation through its phosphotyrosine-binding (PTB domain by competing with fibrinogen for alphaIIbbeta3 integrin receptor binding by an unknown mechanism. METHODOLOGY/PRINCIPAL FINDINGS: Using protein-lipid overlay and liposome-binding assays, we identified that the N-terminal region of Dab2, including its PTB domain (N-PTB, specifically interacts with sulfatides. Moreover, we determined that such interaction is mediated by two conserved basic motifs with a dissociation constant (K(d of 0.6 microM as estimated by surface plasmon resonance (SPR analysis. In addition, liposome-binding assays combined with mass spectroscopy studies revealed that thrombin, a strong platelet agonist, cleaved N-PTB at a site located between the basic motifs, a region that becomes protected from thrombin cleavage when bound to sulfatides. Sulfatides on the platelet surface interact with coagulation proteins, playing a major role in haemostasis. Our results show that sulfatides recruit N-PTB to the platelet surface, sequestering it from integrin receptor binding during platelet activation. This is a transient recruitment that follows N-PTB internalization by an actin-dependent process. CONCLUSIONS/SIGNIFICANCE: Our experimental data support a model where two pools of Dab2 co-exist at the platelet surface, in both sulfatide- and integrin receptor-bound states, and their balance controls the extent of the clotting response.

  15. Acute platelet changes after large meals of saturated and unsaturated fats.

    Science.gov (United States)

    O'Brien, J R; Etherington, M D; Jamieson, S

    1976-04-24

    Large amounts of saturated fats (S.F.) or unsaturated fats (U.S.F.) were given to healthy volunteers at a single meal. The heparin thrombin clotting-time, which may measure platelet factor 4 released from platelets into the plasma, was shortened after S.F. and prolonged after U.S.F. The antithrombin clotting activity decreased after S.F. and increased after U.S.F. The platelet-count decreased and the platelet volume increased after both S.F. and U.S.F.

  16. Platelet microvesicles in health and disease.

    Science.gov (United States)

    Melki, Imene; Tessandier, Nicolas; Zufferey, Anne; Boilard, Eric

    2017-05-01

    Interest in cell-derived extracellular vesicles and their physiological and pathological implications is constantly growing. Microvesicles, also known as microparticles, are small extracellular vesicles released by cells in response to activation or apoptosis. Among the different microvesicles present in the blood of healthy individuals, platelet-derived microvesicles (PMVs) are the most abundant. Their characterization has revealed a heterogeneous cargo that includes a set of adhesion molecules. Similarly to platelets, PMVs are also involved in thrombosis through support of the coagulation cascade. The levels of circulatory PMVs are altered during several disease manifestations such as coagulation disorders, rheumatoid arthritis, systemic lupus erythematosus, cancers, cardiovascular diseases, and infections, pointing to their potential contribution to disease and their development as a biomarker. This review highlights recent findings in the field of PMV research and addresses their contribution to both healthy and diseased states.

  17. Effects of platelet-poor plasma, platelet-rich plasma, and platelet-rich fibrin on healing of extraction sockets with buccal dehiscence in dogs.

    Science.gov (United States)

    Hatakeyama, Ichiro; Marukawa, Eriko; Takahashi, Yukinobu; Omura, Ken

    2014-02-01

    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.

  18. Fuel Oxidizer Reaction Products (FORP) Contamination of Service Module (SM) and Release of N-nitrosodimethylamine(NDMA)in a Humid Environment from Crew EVA Suits Contaminated with FORP

    Science.gov (United States)

    Schmidl, William; Mikatarian, Ron; Lam, Chiu-Wing; West, Bil; Buchanan, Vanessa; Dee, Louis; Baker, David; Koontz, Steve

    2004-01-01

    The Service Module (SM) is an element of the Russian Segment of the International Space Station (ISS). One of the functions of the SM is to provide attitude control for the ISS using thrusters when the U.S. Control Moment Gyros (CMG's) must be desaturated. Prior to an Extravehicular Activity (EVA) on the Russian Segment, the Docking Compartment (DC1) is depressurized, as it is used as an airlock. When the DC1 is depressurized, the CMG's margin of momentum is insufficient and the SM attitude control thrusters need to fire to desaturate the CMG's. SM roll thruster firings induce contamination onto adjacent surfaces with Fuel Oxidizer Reaction Products (FORP). FORP is composed of both volatile and non-volatile components. One of the components of FORP is the potent carcinogen N-nitrosdimethylamine (NDMA). Since the EVA crewmembers often enter the area surrounding the thrusters for tasks on the aft end of the SM and when translating to other areas of the Russian Segment, the presence of FORP is a concern. This paper will discuss FORP contamination of the SM surfaces, the release of NDMA in a humid environment from crew EVA suits, if they happen to be contaminated with FORP, and the toxicological risk associated with the NDMA release.

  19. Prophylactic platelets in dengue

    DEFF Research Database (Denmark)

    Whitehorn, James; Rodriguez Roche, Rosmari; Guzman, Maria G

    2012-01-01

    of platelets in dengue. Respondents were all physicians involved with the treatment of patients with dengue. Respondents were asked that their answers reflected what they would do if they were the treating physician. We received responses from 306 physicians from 20 different countries. The heterogeneity...

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

    Science.gov (United States)

    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.

  1. Platelets possess functional TGF-beta receptors and Smad2 protein.

    Science.gov (United States)

    Lev, P R; Salim, J P; Marta, R F; Osorio, M J Mela; Goette, N P; Molinas, F C

    2007-02-01

    TGF-beta1 plays a main role in tissue repair by regulating extracellular matrix production and tissue granulation. Platelets are one of the main sources of this cytokine in the circulation. The aim of this study was to evaluate the presence of the TGF-beta receptors on platelets, the effect of TGF-beta1 on platelet aggregation and the underlying intracellular mechanisms. TGF-beta receptors on platelets were studied by flow cytometry and their mRNA by PCR. Platelet aggregation was assessed by turbidimetric methods and intracellular pathways by Western blot. TGF-beta receptor type II and mRNA codifying for TbetaRI and TbetaRII were found in platelets. We demonstrated that TGF-beta1 did not trigger platelet aggregation by itself but had a modulating effect on ADP-induced platelet aggregation. Either inhibition or increase in platelet aggregation, depending on the exposure time to TGF-beta1 and the ADP concentration used, were shown. We found that platelets possess Smad2 protein and that its phosphorylation state is increased after exposure to TGF-beta1. Besides, TGF-beta1 modified the pattern of ADP-induced tyrosine phosphorylation. Increased phosphorylation levels of 64-, 80- and 125-kDa proteins during short time incubation with TGF-beta1 and increased phosphorylation of 64- and 125-kDa proteins after longer incubation were observed. The modulating effect of TGF-beta1 on platelet aggregation could play a role during pathological states in which circulating TGF-beta1 levels are increased and intravascular platelet activation is present, such as myeloproliferative disorders. In vascular injury, in which platelet activation followed by granule release generates high local ADP concentrations, it could function as a physiological mechanism of platelet activation control.

  2. Rho GTPases in platelet function.

    Science.gov (United States)

    Aslan, J E; McCarty, O J T

    2013-01-01

    The Rho family of GTP binding proteins, also commonly referred to as the Rho GTPases, are master regulators of the platelet cytoskeleton and platelet function. These low-molecular-weight or 'small' GTPases act as signaling switches in the spatial and temporal transduction, and amplification of signals from platelet cell surface receptors to the intracellular signaling pathways that drive platelet function. The Rho GTPase family members RhoA, Cdc42 and Rac1 have emerged as key regulators in the dynamics of the actin cytoskeleton in platelets and play key roles in platelet aggregation, secretion, spreading and thrombus formation. Rho GTPase regulators, including GEFs and GAPs and downstream effectors, such as the WASPs, formins and PAKs, may also regulate platelet activation and function. In this review, we provide an overview of Rho GTPase signaling in platelet physiology. Previous studies of Rho GTPases and platelets have had a shared history, as platelets have served as an ideal, non-transformed cellular model to characterize Rho function. Likewise, recent studies of the cell biology of Rho GTPase family members have helped to build an understanding of the molecular regulation of platelet function and will continue to do so through the further characterization of Rho GTPases as well as Rho GAPs, GEFs, RhoGDIs and Rho effectors in actin reorganization and other Rho-driven cellular processes. © 2012 International Society on Thrombosis and Haemostasis.

  3. Toxicological effects of beryllium on platelets and vascular endothelium.

    Science.gov (United States)

    Togna, G; Togna, A R; Russo, P; Caprino, L

    1997-06-01

    Although ample research has described the toxic effects of the metal beryllium on the respiratory apparatus, less is known about its effects on the vascular apparatus, including pulmonary blood vessels. We investigated the in vitro effects of beryllium on endothelial vascular adenosine diphosphatase activity and prostacyclin production in bovine aortic endothelium, and on nitric oxide release in isolated rabbit arteries. Rabbit and human platelet responsiveness was also evaluated. Beryllium inhibited vascular endothelial adenosine diphosphatase activity, prostacyclin production, and nitric oxide release, thus inducing functional alterations in vascular endothelial cells. It also induced platelet hyperreactivity to arachidonic acid, as shown by a lowering of the threshold of aggregating concentration and by concurrently increasing thromboxane production. In contrast, beryllium left the response to aggregating and nonaggregating concentrations of ADP and collagen unchanged. These findings show that beryllium may impair some vascular endothelial functions and alter the interaction between platelet and endothelial mediators.

  4. VAMP-7 links granule exocytosis to actin reorganization during platelet activation.

    Science.gov (United States)

    Koseoglu, Secil; Peters, Christian G; Fitch-Tewfik, Jennifer L; Aisiku, Omozuanvbo; Danglot, Lydia; Galli, Thierry; Flaumenhaft, Robert

    2015-07-30

    Platelet activation results in profound morphologic changes accompanied by release of granule contents. Recent evidence indicates that fusion of granules with the plasma membrane during activation provides auxiliary membrane to cover growing actin structures. Yet little is known about how membrane fusion is coupled with actin reorganization. Vesicle-associated membrane protein (VAMP)-7 is found on platelet vesicles and possesses an N-terminal longin domain capable of linking exocytosis to cytoskeletal remodeling. We have evaluated platelets from VAMP-7(-/-) mice to determine whether this VAMP isoform contributes to granule release and platelet spreading. VAMP-7(-/-) platelets demonstrated a partial defect in dense granule exocytosis and impaired aggregation. α Granule exocytosis from VAMP-7(-/-) platelets was diminished both in vitro and in vivo during thrombus formation. Consistent with a role of VAMP-7 in cytoskeletal remodeling, spreading on matrices was decreased in VAMP-7(-/-) platelets compared to wild-type controls. Immunoprecipitation of VAMP-7 revealed an association with VPS9-domain ankyrin repeat protein (VARP), an adaptor protein that interacts with both membrane-bound and cytoskeleton proteins and with Arp2/3. VAMP-7, VARP, and Arp2/3 localized to the platelet periphery during spreading. These studies demonstrate that VAMP-7 participates in both platelet granule secretion and spreading and suggest a mechanism whereby VAMP-7 links granule exocytosis with actin reorganization.

  5. Prostaglandin A1 inhibits increases in intracellular calcium concentration, TXA2 production and platelet activation

    Institute of Scientific and Technical Information of China (English)

    Yi ZHU; Zhen-lun GU; Zhong-qin LIANG; Hui-lin ZHANG; Zheng-hong QIN

    2006-01-01

    Aim: In our previous studies we found that cyclopentenane prostaglandin A1 (PGA1) had neuroprotective effects in a rodent ischemic model. In the present study we aimed to investigate the inhibitory effect of PGA1 on platelet function. Method: The rate of aggregation of human platelets was measured by using turbidimetry. The rate of adhesion of platelets to cultured endothelial cells was determined by using [3H]-adenine labeled platelets. 5-Hydroxytryptamine release from platelets was measured with O-phthaldialdehyde fluorospectrophotometry. The levels of TXB2, a stable metabolite of TXA2, were determined by radioimmunoassay. Alternations in platelet morphology were observed using an electron microscope, and the intraplatelet free calcium concentrations were measured with Fluo-3/AM FCM assay. Results: PGA1 significantly inhibited thrombin-collagen-and ADP-induced aggregation and adhesion of platelets. The morphological changes of platelets induced by thrombin were blocked by PGA1. PGA1 inhibited the release of 5-hydroxytyptamine from dense granules and the synthesis of TXA2. Conclusion: PGA1 inhibits the activation of platelets probably through blocking increases in intracellular calcium concentration and TXA2 synthesis.

  6. Comparison of platelets characteristics according to various processing methods

    Directory of Open Access Journals (Sweden)

    O. V. Karpova

    2014-01-01

    Full Text Available To date different techniques of platelet concentrates (PC preparation and processing are proposed to achieve the best efficiency of transfusions and to minimize the risks post-transfusion reactions. However, data on the impact of different approaches to PC preparation and processing on morphological and functional characteristics of platelets and, as a consequence, the clinical efficacy of transfusions is controversial. In this paper we analyzed the impact of the platelet storage solution and different methods of pathogen inactivation (X-rays, UV-irradiation after photosensitization with riboflavin on morphological and functional parameters of platelets. Our findings allow optimizing the technology of preparation and processing of PC to achieve greater effectiveness of transfusion therapy.

  7. Pathogenic role of platelets in rheumatoid arthritis and systemic autoimmune diseases

    Science.gov (United States)

    Harifi, Ghita; Sibilia, Jean

    2016-01-01

    Well-recognized for their role in vascular homoeostasis, platelets may play a major role in inflammation and immunomodulation. Substantial data are emerging on the pathogenic involvement of platelets in inflammatory arthritis and autoimmune diseases, indicating the existence of crosstalk between the coagulation and inflammation system. Upon activation, platelets release pro-inflammatory platelets microparticles, which interact with leucocytes leading to joint and systemic inflammation in rheumatoid arthritis. Platelets activation by immune complexes activate dendritic cells promoting the secretion of interferon alpha, which has a key role in the development of systemic lupus erythematous. In this review, we discuss the current data on the role of platelets in the pathophysiology of inflammatory arthritis and various autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus, and systemic sclerosis. PMID:27052277

  8. The influence of platelet- derived products on angiogenesis and tissue repair: a concise update

    Directory of Open Access Journals (Sweden)

    Constanza E Martínez

    2015-10-01

    Full Text Available Platelet degranulation allows the release of a large amount of soluble mediators, is an essential step for wound healing initiation, and stimulates clotting and angiogenesis. The latter process is one of the most critical biological events observed during tissue repair,increasing the growth of blood vessels in the maturing wound. Angiogenesis requires the action of a variety of growth factors that act in an appropriate physiological ratio to assure functional blood vessel restoration. Platelets release main regulators of angiogenesis: Vascular Endothelial Growth Factors (VEGFs, basic fibroblast growth factor (FGF-2, and Platelet derived growth factors (PDGFs, among others. In order to stimulate tissue repair, platelet derived fractions have been used as an autologous source of growth factors and biomolecules, namely Platelet Rich Plasma (PRP, Platelet Poor Plasma (PPP and Platelet Rich Fibrin(PRF. The continuous release of these growth factors has been proposed to promote angiogenesis both in vitro and in vivo. Considering the existence of clinical trials currently evaluating the efficacy of autologous PRP, the present review analyses fundamental questions regarding the putative role of platelet derived fractions as regulators of angiogenesis and evaluates the possible clinical implications of these formulations.

  9. The influence of platelet-derived products on angiogenesis and tissue repair: a concise update

    Science.gov (United States)

    Martínez, Constanza E.; Smith, Patricio C.; Palma Alvarado, Verónica A.

    2015-01-01

    Platelet degranulation allows the release of a large amount of soluble mediators, is an essential step for wound healing initiation, and stimulates clotting, and angiogenesis. The latter process is one of the most critical biological events observed during tissue repair, increasing the growth of blood vessels in the maturing wound. Angiogenesis requires the action of a variety of growth factors that act in an appropriate physiological ratio to assure functional blood vessel restoration. Platelets release main regulators of angiogenesis: Vascular Endothelial Growth Factors (VEGFs), basic fibroblast growth factor (FGF-2), and Platelet derived growth factors (PDGFs), among others. In order to stimulate tissue repair, platelet derived fractions have been used as an autologous source of growth factors and biomolecules, namely Platelet Rich Plasma (PRP), Platelet Poor Plasma (PPP), and Platelet Rich Fibrin (PRF). The continuous release of these growth factors has been proposed to promote angiogenesis both in vitro and in vivo. Considering the existence of clinical trials currently evaluating the efficacy of autologous PRP, the present review analyses fundamental questions regarding the putative role of platelet derived fractions as regulators of angiogenesis and evaluates the possible clinical implications of these formulations. PMID:26539125

  10. Murine monoclonal antibody to platelet factor 4/heparin complexes as a potential reference standard for platelet activation assays in heparin-induced thrombocytopenia.

    Science.gov (United States)

    Asada, Reiko; Wanaka, Keiko; Walenga, Jeanine; Prechel, Margaret; Miyashita, Kumiko; Escalante, Vicki; Kaneko, Chieko; Hoshino, Nobuhiro; Oosawa, Mitsuru; Matsuo, Miyako

    2013-01-01

    Quality control of the platelet activation assays to diagnose heparin-induced thrombocytopenia (HIT), (14)C-serotonin release assay (SRA) and platelet aggregation test (PAT) has yet to be established due to lack of reference standards and the difficulty of obtaining significant amounts of HIT antibodies from patients with HIT. We prepared a murine monoclonal antibody to human platelet factor 4 (hPF4)/heparin complexes (HIT-MoAb) and investigated the platelet activating action of HIT-MoAb by using SRA and PAT. The HIT-MoAb activated human platelets at low heparin concentration and the platelet activations were inhibited at high heparin concentration in both SRA and PAT. The HIT-MoAb produced a concentration-dependent effect. Moreover, the platelet activation at low heparin concentration was inhibited by anti-FcγRIIa antibody. These results indicated that HIT-MoAb has characteristics similar to human HIT antibodies regarding heparin-dependent platelet activation. Therefore, it is suggested that HIT-MoAb has the potential to be a positive control or reference standard in platelet activation assays.

  11. Human platelets express Toll-like receptor 3 and respond to poly I:C.

    Science.gov (United States)

    Anabel, Antonio-Santos; Eduardo, Pérez-Campos; Pedro Antonio, Hernández-Cruz; Carlos, Solórzano-Mata; Juana, Narváez-Morales; Honorio, Torres-Aguilar; Nicolás, Villegas-Sepúlveda; Sergio Roberto, Aguilar-Ruiz

    2014-12-01

    Platelets functions in hemostasis have been widely studied. Currently, growing evidence shows that platelets have also a role in the immune innate response. Recently, protein expression of Toll-like receptors (TLR's) 2, 4, 7, 8, and 9, and the presence of TLRs 1 and 6 mRNA in human platelets was described. Up to now the functionality of TLR-2, 4 and 9 in human platelets has been demonstrated. Due to the relevance of TLRs functions to PAMPS (pathogen-associated molecular patterns) recognizing, we evaluated the presence of TLR3 in human platelets founding low percentages of platelets expressing surface or intracellular TLR3 protein. The activation with thrombin induced an increase in the percentage of platelets expressing surface TLR3 and higher levels of TLR3 expression in the whole population. Human platelets responded to poly I:C by increasing [Ca(2+)]i, the percentages of cells expressing TLR4 and CD62P, and by releasing CXCL4 and IL-1β in comparison to unstimulated platelets. These results demonstrate that human platelets express TLR3 and are capable of responding to poly I:C, suggesting that these cells might influence the immune innate response when detecting viral dsRNA. Copyright © 2014 American Society for Histocompatibility and Immunogenetics. Published by Elsevier Inc. All rights reserved.

  12. Myeloperoxidase modulates human platelet aggregation via actin cytoskeleton reorganization and store-operated calcium entry

    Directory of Open Access Journals (Sweden)

    Irina V. Gorudko

    2013-07-01

    Myeloperoxidase (MPO is a heme-containing enzyme released from activated leukocytes into the extracellular space during inflammation. Its main function is the production of hypohalous acids that are potent oxidants. MPO can also modulate cell signaling and inflammatory responses independently of its enzymatic activity. Because MPO is regarded as an important risk factor for cardiovascular diseases associated with increased platelet activity, we studied the effects of MPO on human platelet functional properties. Laser scanning confocal microscopy was used to reveal carbohydrate-independent MPO binding to human platelet membrane. Adding MPO to platelets did not activate their aggregation under basal conditions (without agonist. In contrast, MPO augmented agonist-induced platelet aggregation, which was not prevented by MPO enzymatic activity inhibitors. It was found that exposure of platelets to MPO leads to actin cytoskeleton reorganization and an increase in their elasticity. Furthermore, MPO evoked a rise in cytosolic Ca2+ through enhancement of store-operated Ca2+ entry (SOCE. Together, these findings indicate that MPO is not a direct agonist but rather a mediator that binds to human platelets, induces actin cytoskeleton reorganization and affects the mechanical stiffness of human platelets, resulting in potentiating SOCE and agonist-induced human platelet aggregation. Therefore, an increased activity of platelets in vascular disease can, at least partly, be provided by MPO elevated concentrations.

  13. Platelets Mediate Host Defense against Staphylococcus aureus through Direct Bactericidal Activity and by Enhancing Macrophage Activities.

    Science.gov (United States)

    Ali, Ramadan A; Wuescher, Leah M; Dona, Keith R; Worth, Randall G

    2017-01-01

    Platelets are the chief effector cells in hemostasis. However, recent evidence suggests they have multiple roles in host defense against infection. Reports by us and others showed that platelets functionally contribute to protection against Staphylococcus aureus infection. In the current study, the capacity of mouse platelets to participate in host defense against S. aureus infection was determined by assessing two possibilities. First, we determined the ability of platelets to kill S. aureus directly; and, second, we tested the possibility that platelets enhance macrophage phagocytosis and intracellular killing of S. aureus In this study we report evidence in support of both mechanisms. Platelets effectively killed two different strains of S. aureus. A clinical isolate of methicillin-resistant S. aureus was killed by platelets (>40% killing in 2 h) in a thrombin-dependent manner whereas a methicillin-sensitive strain was killed to equal extent but did not require thrombin. Interestingly, thrombin-stimulated platelets also significantly enhanced peritoneal macrophage phagocytosis of both methicillin-resistant S. aureus and methicillin-sensitive S. aureus by >70%, and restricted intracellular growth by >40%. Enhancement of macrophage anti-S. aureus activities is independent of contact with platelets but is mediated through releasable products, namely IL-1β. These data confirm our hypothesis that platelets participate in host defense against S. aureus both through direct killing of S. aureus and enhancing the antimicrobial function of macrophages in protection against S. aureus infection. Copyright © 2016 by The American Association of Immunologists, Inc.

  14. Matrix metalloproteinase-2 enhances platelet deposition on collagen under flow conditions.

    Science.gov (United States)

    Guglielmini, Giuseppe; Appolloni, Viviana; Momi, Stefania; De Groot, Philip G; Battiston, Monica; De Marco, Luigi; Falcinelli, Emanuela; Gresele, Paolo

    2016-01-01

    Platelets contain and release matrix metalloproteinase-2 (MMP-2) that in turn potentiates platelet aggregation. Platelet deposition on a damaged vascular wall is the first, crucial, step leading to thrombosis. Little is known about the effects of MMP-2 on platelet activation and adhesion under flow conditions. We studied the effect of MMP-2 on shear-dependent platelet activation using the O'Brien filtration system, and on platelet deposition using a parallel-plate perfusion chamber. Preincubation of human whole blood with active MMP-2 (50 ng/ml, i.e. 0.78 nM) shortened filter closure time (from 51.8 ± 3.6 sec to 40 ± 2.7 sec, pMMP-2 inhibitor. High shear stress induced the release of MMP-2 from platelets, while TIMP-2 levels were not significantly reduced, therefore, the MMP-2/TIMP-2 ratio increased significantly showing enhanced MMP-2 activity. Preincubation of whole blood with active MMP-2 (0.5 to 50 ng/ml, i.e 0.0078 to 0.78 nM) increased dose-dependently human platelet deposition on collagen under high shear-rate flow conditions (3000 sec⁻¹) (maximum +47.0 ± 11.9%, pMMP-2 inhibitor reduced platelet deposition. In real-time microscopy studies, increased deposition of platelets on collagen induced by MMP-2 started 85 sec from the beginning of perfusion, and was abolished by a GPIIb/IIIa antagonist, while MMP-2 had no effect on platelet deposition on fibrinogen or VWF. Confocal microscopy showed that MMP-2 enhances thrombus volume (+20.0 ± 3.0% vs control) rather than adhesion. In conclusion, we show that MMP-2 potentiates shear-induced platelet activation by enhancing thrombus formation.

  15. Platelet Dysfunction in Patients with Chronic Myeloid Leukemia: Does Imatinib Mesylate Improve It?

    Directory of Open Access Journals (Sweden)

    Olga Meltem Akay

    2016-05-01

    Full Text Available Objective: The aim of this study was to investigate the effects of imatinib mesylate on platelet aggregation and adenosine triphosphate (ATP release in chronic myeloid leukemia patients. Materials and Methods: Platelet aggregation and ATP release induced by 5.0 mM adenosine diphosphate, 0.5 mM arachidonic acid, 1.0 mg/ mL ristocetin, and 2 µg/mL collagen were studied by whole blood platelet lumi-aggregometer in 20 newly diagnosed chronic myeloid leukemia patients before and after imatinib mesylate treatment. Results: At the time of diagnosis, 17/20 patients had abnormal platelet aggregation results; 8 (40% had hypoactivity, 6 (30% had hyperactivity, and 3 (15% had mixed hypo- and hyperactivity. Repeat platelet aggregation studies were performed after a mean of 19 months (min: 5 months-max: 35 months in all patients who received imatinib mesylate during this period. After therapy, 18/20 (90% patients had abnormal laboratory results; 12 (60% had hypoactive platelets, 4 (20% had mixed hypo- and hyperactive platelets, and 2 (10% had hyperactive platelets. Three of the 8 patients with initial hypoactivity remained hypoactive, while 2 developed a mixed picture, 2 became hyperactive, and 1 normalized. Of the 6 patients with initial hyperactivity, 4 became hypoactive and 2 developed a mixed pattern. All of the 3 patients with initial hypo- and hyperactivity became hypoactive. Finally, 2 of the 3 patients with initial normal platelets became hypoactive while 1 remained normal. There was a significant decrease in ristocetin-induced platelet aggregation after therapy (p0.05. Conclusion: These findings indicate that a significant proportion of chronic myeloid leukemia patients have different patterns of platelet function abnormalities and imatinib mesylate has no effect on these abnormalities, with a significant impairment in ristocetin-induced platelet aggregation.

  16. PGE2 decreases reactivity of human platelets by activating EP2 and EP4.

    Science.gov (United States)

    Smith, James P; Haddad, Elias V; Downey, Jason D; Breyer, Richard M; Boutaud, Olivier

    2010-07-01

    Platelet hyperreactivity associates with cardiovascular events in humans. Studies in mice and humans suggest that prostaglandin E2 (PGE2) regulates platelet activation. In mice, activation of the PGE2 receptor subtype 3 (EP3) promotes thrombosis, but the significance of EP3 in humans is less well understood. To characterize the regulation of thromboxane-dependent human platelet activation by PGE2. Platelets collected from nineteen healthy adults were studied using an agonist of the thromboxane receptor (U46,619), PGE2, and selective agonists and/or antagonists of the EP receptor subtypes. Platelet activation was assayed by (1) optical aggregometry, (2) measurement of dense granule release, and (3) single-platelet counting. Healthy volunteers demonstrated significant interindividual variation in platelet response to PGE2. PGE2 completely inhibited U46,619-induced platelet aggregation and ATP release in 26% of subjects; the remaining 74% had partial or no response to PGE2. Antagonism of EP4 abolished the inhibitory effect of PGE2. In all volunteers, a selective EP2 agonist inhibited U46,619-induced aggregation. Furthermore, the selective EP3 antagonist DG-041 converted all PGE2 nonresponders to full responders. There is significant interindividual variation of platelet response to PGE2 in humans. The balance between EP2, EP3, and EP4 activation determines its net effect. PGE2 can prevent thromboxane-induced platelet aggregation in an EP4-dependent manner. EP3 antagonism converts platelets of nonresponders to a PGE2-responsive phenotype. These data suggest that therapeutic targeting of EP pathways may have cardiovascular benefit by decreasing platelet reactivity. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  17. Expansion of the neonatal platelet mass is achieved via an extension of platelet lifespan

    OpenAIRE

    Liu, Zhi-Jian; Hoffmeister, Karin M.; Hu, Zhongbo; Mager, Donald E.; Ait-Oudhia, Sihem; Debrincat, Marlyse A.; Pleines, Irina; Josefsson, Emma C.; Benjamin T Kile; Italiano, Joseph; Ramsey, Haley; Grozovsky, Renata; Veng-Pedersen, Peter; Chavda, Chaitanya; Sola-Visner, Martha

    2014-01-01

    Rapid growth and rising platelet counts result in a significant expansion of platelet mass during neonatal life.The rise in platelet counts is mediated by a prolongation in the neonatal platelet lifespan.

  18. PREGNANCY WITH PLATELET FUNCTION DISORDER

    Directory of Open Access Journals (Sweden)

    Sheila K

    2014-01-01

    Full Text Available latelets play a vital role in haemostasis . Antenatal patients with platelet function disorders should be managed in tertiary care centres that are well equipped to tackle any obstetric haemorrhage that can ensue during labour and delivery . Primi gravida was admitted for safe confinement . She had been evaluated earlier for complaints of multiple episodes of mucosal bleeding . On evaluation she had nor mal platelet counts and coagulation factor assay was normal . Platelet aggregometry revealed mild disorder of platelet aggregation . She was planned for induction of labour after arranging enough blood and blood products . She got into active labour and was p ut on syntocinon augmentation . She had emergency Caesarean section for foetal distress . Oxytocics were given proactively . Intraoperatively platelet transfusions and tranexamic acid infusion were given . Complete haemostasis was achieved . She had an uneventf ul postoperative period . Patients with functional platelet disorders can be successfully managed with local application of antifibrinolytic agents like tranexamic acid , in case of minor bleeds . Platelet transfusions are very effective in tackling major ble eds , especially during surgeries and for obstetric indications . If a patient has the history of clinically significant bleeding suggestive of platelet dysfunction , appropriate platelet function tests should be obtained so that the risk of bleeding can be adequately assessed and therapy chosen more rationally . . In obstetric practice the response of such patients to platelet transfusions has been excellent

  19. 葡萄糖酸钙口服液在预防机采血小板献血不良反应中的应用%Preventive Efficacy of Calcium Gluconate Oral Liquid against Apheresis Platelet Donation-induced Adverse Reaction

    Institute of Scientific and Technical Information of China (English)

    古贤清

    2015-01-01

    OBJECTIVE:To evaluate the preventive efficacy of calcium gluconate oral liquid against apheresis platelet donation-induced adverse reaction.METHODS:From July 2012 to June 2013 , a total of 248 cases of apheresis platelet donors in our blood center were assigned to control group giving none treatment during blood collection, with 1 treatment unit of blood collected once in 140 cases and 2 treatment units of blood collected once in 108 cases; from July 2013 to June 2014, another 288 cases of apheresis platelet donors in the observation group were administered with calcium gluconate oral liquid before blood collection, with 1 treatment unit of blood collected once in 152 cases and 2 treatment units of blood collected once in 136 cases.The incidence of adverse reactions was compared between the two groups.RESULTS:Adverse reactions were noted in 2.63% ( 4/152 ) of the one treatment unit apheresis platelet donors, 3.68%(5/136) of the two treatment units apheresis platelet donors and 3.13%(9/288) of the total patients in the observation group, which were significantly less than in the control group [ 22.14%(31/140), 35.19%(38/108) and 27.82% (69/248) respectively] (P<0.05).The incidence of citrate reaction in the observation group was significantly less than in the control group [55.56%(5/9) vs.81.16%(56/69);P<0.05].CONCLUSIONS:Citrate reaction is the predominant adverse reaction in apheresis platelet donors.Administration of calcium gluconate oral liquid before platelet collection can significantly prevent or reduce the incidence of apheresis platelet donation-induced adverse reaction, which thus is worthy of clinical recommendation.%目的:观察葡萄糖酸钙口服液预防机采血小板献血不良反应的效果。方法:选择惠州市中心血站2012年7月—2013年6月248例机采血小板献血者作为对照组,采血期间不做任何处理,其中140例1次采1个治疗单位,108例1次采2个治疗单位;选择2013年7月—2014年6月288例采

  20. Effects of hormones on platelet aggregation.

    Science.gov (United States)

    Farré, Antonio López; Modrego, Javier; Zamorano-León, José J

    2014-04-01

    Platelets and their activation/inhibition mechanisms play a central role in haemostasis. It is well known agonists and antagonists of platelet activation; however, during the last years novel evidences of hormone effects on platelet activation have been reported. Platelet functionality may be modulated by the interaction between different hormones and their platelet receptors, contributing to sex differences in platelet function and even in platelet-mediated vascular damage. It has suggested aspects that apparently are well established should be reviewed. Hormones effects on platelet activity are included among them. This article tries to review knowledge about the involvement of hormones in platelet biology and activity.

  1. The role of platelets in the pathophysiology of asthma.

    Science.gov (United States)

    Kornerup, K N; Page, C P

    2007-08-01

    The incidence of asthma is on the increase worldwide, yet the pathogenesis of this disease is still not fully understood. Many recent drug trials have had disappointing results, thus fuelling the need for more research to be undertaken in this area. Substantial evidence suggests an important role for platelets in various inflammatory diseases, including atherosclerosis, rheumatoid arthritis, eczema, allergic rhinitis and asthma. In asthma, platelets have been found to actively participate in most of its main features, including bronchial hyperresponsiveness, bronchoconstriction, airway inflammation and airway remodelling. It has recently become clear that platelet-release products, as well as the expression of adhesion molecules on the platelet surface and the ability to undergo chemotaxis, are all involved in these processes. This review focuses on both experimental and clinical studies available to date that have investigated the role of platelets in the pathophysiology of asthma. Taken together, the evidence points toward platelets being an attractive new target in the area of asthma research; a target with much-needed novel therapeutic potential.

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

    Science.gov (United States)

    Gresele, Paolo; Bury, Loredana; Falcinelli, Emanuela

    2016-04-01

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

  3. Identification of the platelet ADP receptor targeted by antithrombotic drugs.

    Science.gov (United States)

    Hollopeter, G; Jantzen, H M; Vincent, D; Li, G; England, L; Ramakrishnan, V; Yang, R B; Nurden, P; Nurden, A; Julius, D; Conley, P B

    2001-01-11

    Platelets have a crucial role in the maintenance of normal haemostasis, and perturbations of this system can lead to pathological thrombus formation and vascular occlusion, resulting in stroke, myocardial infarction and unstable angina. ADP released from damaged vessels and red blood cells induces platelet aggregation through activation of the integrin GPIIb-IIIa and subsequent binding of fibrinogen. ADP is also secreted from platelets on activation, providing positive feedback that potentiates the actions of many platelet activators. ADP mediates platelet aggregation through its action on two G-protein-coupled receptor subtypes. The P2Y1 receptor couples to Gq and mobilizes intracellular calcium ions to mediate platelet shape change and aggregation. The second ADP receptor required for aggregation (variously called P2Y(ADP), P2Y(AC), P2Ycyc or P2T(AC)) is coupled to the inhibition of adenylyl cyclase through Gi. The molecular identity of the Gi-linked receptor is still elusive, even though it is the target of efficacious antithrombotic agents, such as ticlopidine and clopidogrel and AR-C66096 (ref. 9). Here we describe the cloning of this receptor, designated P2Y12, and provide evidence that a patient with a bleeding disorder has a defect in this gene. Cloning of the P2Y12 receptor should facilitate the development of better antiplatelet agents to treat cardiovascular diseases.

  4. Platelet aggregation following trauma

    DEFF Research Database (Denmark)

    Windeløv, Nis A; Sørensen, Anne M; Perner, Anders

    2014-01-01

    We aimed to elucidate platelet function in trauma patients, as it is pivotal for hemostasis yet remains scarcely investigated in this population. We conducted a prospective observational study of platelet aggregation capacity in 213 adult trauma patients on admission to an emergency department (ED......). Inclusion criteria were trauma team activation and arterial cannula insertion on arrival. Blood samples were analyzed by multiple electrode aggregometry initiated by thrombin receptor agonist peptide 6 (TRAP) or collagen using a Multiplate device. Blood was sampled median 65 min after injury; median injury...... severity score (ISS) was 17; 14 (7%) patients received 10 or more units of red blood cells in the ED (massive transfusion); 24 (11%) patients died within 28 days of trauma: 17 due to cerebral injuries, four due to exsanguination, and three from other causes. No significant association was found between...

  5. Nanoparticle-induced platelet aggregation and vascular thrombosis.

    Science.gov (United States)

    Radomski, Anna; Jurasz, Paul; Alonso-Escolano, David; Drews, Magdalena; Morandi, Maria; Malinski, Tadeusz; Radomski, Marek W

    2005-11-01

    Ever increasing use of engineered carbon nanoparticles in nanopharmacology for selective imaging, sensor or drug delivery systems has increased the potential for blood platelet-nanoparticle interactions. We studied the effects of engineered and combustion-derived carbon nanoparticles on human platelet aggregation in vitro and rat vascular thrombosis in vivo. Multiplewall (MWNT), singlewall (SWNT) nanotubes, C60 fullerenes (C60CS) and mixed carbon nanoparticles (MCN) (0.2-300 microg ml(-1)) were investigated. Nanoparticles were compared with standard urban particulate matter (SRM1648, average size 1.4 microm). Platelet function was studied using lumi aggregometry, phase-contrast, immunofluorescence and transmission electron microscopy, flow cytometry, zymography and pharmacological inhibitors of platelet aggregation. Vascular thrombosis was induced by ferric chloride and the rate of thrombosis was measured, in the presence of carbon particles, with an ultrasonic flow probe. Carbon particles, except C60CS, stimulated platelet aggregation (MCN>or=SWNT>MWNT>SRM1648) and accelerated the rate of vascular thrombosis in rat carotid arteries with a similar rank order of efficacy. All particles resulted in upregulation of GPIIb/IIIa in platelets. In contrast, particles differentially affected the release of platelet granules, as well as the activity of thromboxane-, ADP, matrix metalloproteinase- and protein kinase C-dependent pathways of aggregation. Furthermore, particle-induced aggregation was inhibited by prostacyclin and S-nitroso-glutathione, but not by aspirin. Thus, some carbon nanoparticles and microparticles have the ability to activate platelets and enhance vascular thrombosis. These observations are of importance for the pharmacological use of carbon nanoparticles and pathology of urban particulate matter.

  6. Prevalence of Ex Vivo High On-treatment Platelet Reactivity on Antiplatelet Therapy after Transient Ischemic Attack or Ischemic Stroke on the PFA-100(®) and VerifyNow(®).

    LENUS (Irish Health Repository)

    Kinsella, Justin A

    2012-09-12

    BACKGROUND: The prevalence of ex vivo high on-treatment platelet reactivity (HTPR) to commonly prescribed antiplatelet regimens after transient ischemic attack (TIA) or ischemic stroke is uncertain. METHODS: Platelet function inhibition was simultaneously assessed with modified light transmission aggregometry (VerifyNow; Accumetrics Inc, San Diego, CA) and with a moderately high shear stress platelet function analyzer (PFA-100; Siemens Medical Solutions USA, Inc, Malvern, PA) in a pilot, cross-sectional study of TIA or ischemic stroke patients. Patients were assessed on aspirin-dipyridamole combination therapy (n = 51) or clopidogrel monotherapy (n = 25). RESULTS: On the VerifyNow, HTPR on aspirin was identified in 4 of 51 patients (8%) on aspirin-dipyridamole combination therapy (≥550 aspirin reaction units on the aspirin cartridge). Eleven of 25 (44%) patients had HTPR on clopidogrel (≥194 P2Y12 reaction units on the P2Y12 cartridge). On the PFA-100, 21 of 51 patients (41%) on aspirin-dipyridamole combination therapy had HTPR on the collagen-epinephrine (C-EPI) cartridge. Twenty-three of 25 patients (92%) on clopidogrel had HTPR on the collagen-adenosine diphosphate (C-ADP) cartridge. The proportion of patients with antiplatelet HTPR was lower on the VerifyNow than PFA-100 in patients on both regimens (P < .001). CONCLUSIONS: The prevalence of ex vivo antiplatelet HTPR after TIA or ischemic stroke is markedly influenced by the method used to assess platelet reactivity. The PFA-100 C-ADP cartridge is not sensitive at detecting the antiplatelet effects of clopidogrel ex vivo. Larger prospective studies with the VerifyNow and with the PFA-100 C-EPI and recently released Innovance PFA P2Y cartridges (Siemens Medical Solutions USA, Inc) in addition to newer tests of platelet function are warranted to assess whether platelet function monitoring predicts clinical outcome in ischemic cerebrovascular disease.

  7. Gingival tissue-produced inhibition of platelet aggregation and the loss of inhibition in streptozotocin-induced diabetic rats

    Energy Technology Data Exchange (ETDEWEB)

    Kawamura, Keiichiroh; Tamai, Kazuharu; Shirakawa, Masaharu; Okamoto, Hiroshi; Dohi, Toshihiro; Tsujimoto, Akira

    1988-01-01

    Addition of medium incubated with normal rat gingival tissue to platelet-rich plasma inhibited ADP-induced platelet aggregation. The ability of rat gingiva to produce activity inhibiting platelet aggregation was enhanced by the addition of arachidonic acid. Diabetic rat gingiva failed to inhibit platelet aggregation but did produce the anti-platelet aggregating activity in the presence of arachidonic acid. Indomethacin blocked the production of anti-platelet aggregating activity. There was no difference in conversion of (1-/sup 14/C)arachidonic acid to prostaglandins by normal and diabetic rat gingiva. These results suggest that an arachidonic acid metabolite released from gingiva during incubation inhibits platelet aggregation, and the synthesis of the metabolite is impaired in diabetic rat gingiva. A decrease in availability of arachidonic acid may be a causal factor of the defect in diabetic rat gingiva.

  8. A mathematical model for in vitro coagulation of blood: role of platelet count and inhibition

    Indian Academy of Sciences (India)

    M SUSREE; M ANAND

    2017-03-01

    A mechanistic model including the role of platelets is proposed for clot formation and growth in plasma in vitro. Initiation of clot formation is by the addition of tissue factor, and initiation via the intrinsic pathway is neglected. Activation of zymogens follows the extrinsic pathway cascade and reactions on platelet membranes are included. Platelet activation occurs due to thrombin and also due to other activated platelets.Inhibition of the active clotting factors is by ATIII and TFPI, whereas inhibition due to APC is not relevant in the conditions modeled. The model predictions matched existing data for thrombin production in synthetic plasma. The model predicts that inhibition of platelet-driven activation of platelets has a major effect on concentration of activated platelets in PRP, normal plasma and PPP. Inhibition of platelet activation by (other activated) platelets significantly delays thrombin production in PRP and normal plasma as compared to that by thrombin. Further, sensitivity analysis shows that the model is most sensitive to the activation of platelet membrane-bound factor X by the intrinsic tenase complex.

  9. Erythrocyte and platelet proteomics in hematological disorders.

    Science.gov (United States)

    Chakrabarti, Abhijit; Halder, Suchismita; Karmakar, Shilpita

    2016-04-01

    Erythrocytes undergo ineffective erythropoesis, hemolysis, and premature eryptosis in sickle cell disease and thalassemia. Abnormal hemoglobin variants associated with hemoglobinopathy lead to vesiculation, membrane instability, and loss of membrane asymmetry with exposal of phosphatidylserine. This potentiates thrombin generation resulting in activation of the coagulation cascade responsible for subclinical phenotypes. Platelet activation also results in the release of microparticles, which express and transfer functional receptors from platelet membrane, playing key roles in vascular reactivity and activation of intracellular signaling pathways. Over the last decade, proteomics had proven to be an important field of research in studies of blood and blood diseases. Blood cells and its fluidic components have been proven to be easy systems for studying differential expressions of proteins in hematological diseases encompassing hemoglobinopathies, different types of anemias, myeloproliferative disorders, and coagulopathies. Proteomic studies of erythrocytes and platelets reported from several groups have highlighted various factors that intersect the signaling networks in these anucleate systems. In this review, we have elaborated on the current scenario of anucleate blood cell proteomes in normal and diseased individuals and the cross-talk between the two major constituent cell types of circulating blood.

  10. Platelets in inflammation and immunity.

    Science.gov (United States)

    Herter, J M; Rossaint, J; Zarbock, A

    2014-11-01

    The paradigm of platelets as mere mediators of hemostasis has long since been replaced by a dual role: hemostasis and inflammation. Now recognized as key players in innate and adaptive immune responses, platelets have the capacity to interact with almost all known immune cells. These platelet-immune cell interactions represent a hallmark of immunity, as they can potently enhance immune cell functions and, in some cases, even constitute a prerequisite for host defense mechanisms such as NETosis. In addition, recent studies have revealed a new role for platelets in immunity: They are ubiquitous sentinels and rapid first-line immune responders, as platelet-pathogen interactions within the vasculature appear to precede all other host defense mechanisms. Here, we discuss recent advances in our understanding of platelets as inflammatory cells, and provide an exemplary review of their role in acute inflammation.

  11. Estrogen, inflammation, and platelet phenotype.

    Science.gov (United States)

    Miller, Virginia M; Jayachandran, Muthuvel; Hashimoto, Kazumori; Heit, John A; Owen, Whyte G

    2008-01-01

    Although exogenous estrogenic therapies increase the risk of thrombosis, the effects of estrogen on formed elements of blood are uncertain. This article examines the genomic and nongenomic actions of estrogen on platelet phenotype that may contribute to increased thrombotic risk. To determine aggregation, secretion, protein expression, and thrombin generation, platelets were collected from experimental animals of varying hormonal status and from women enrolled in the Kronos Early Estrogen Prevention Study. Estrogen receptor beta predominates in circulating platelets. Estrogenic treatment in ovariectomized animals decreased platelet aggregation and adenosine triphosphate (ATP) secretion. However, acute exposure to 17beta-estradiol did not reverse decreases in platelet ATP secretion invoked by lipopolysaccharide. Thrombin generation was positively correlated to the number of circulating microvesicles expressing phosphatidylserine. Assessing the effect of estrogen treatments on blood platelets may lead to new ways of identifying women at risk for adverse thrombotic events with such therapies.

  12. Complement Activation Alters Platelet Function

    Science.gov (United States)

    2015-12-01

    Award Number: W81XWH-12-1-0523 TITLE: Complement Activation Alters Platelet Function PRINCIPAL INVESTIGATOR: George Tsokos, M.D. CONTRACTING...Activation Alters Platelet Function 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-12-1-0523 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) George Tsokos, M.D...a decreased level of disease. Further studies will expand upon these observations better outlining the function of platelets in the injury associated

  13. Platelet effects on ovarian cancer

    Science.gov (United States)

    Davis, Ashley; Afshar-Kharghan, Vahid; Sood, Anil K.

    2014-01-01

    Growing understanding of the role of thrombocytosis, high platelet turnover, and the presence of activated platelets in the circulation in cancer progression and metastasis has brought megakaryocytes into focus. Platelet biology is essential to hemostasis, vascular integrity, angiogenesis, inflammation, innate immunity, wound healing, and cancer biology. However, before megakaryocyte/platelet-directed therapies can be considered for clinical use, understanding of the mechanism and biology of paraneoplastic thrombocytosis in malignancy is required. Here, we provide an overview of the clinical implications, biological significance, and mechanisms of paraneoplastic thrombocytosis in the context of ovarian cancer. PMID:25023353

  14. Novel aspects of platelet aggregation

    Directory of Open Access Journals (Sweden)

    Roka-Moya Y. M.

    2014-01-01

    Full Text Available The platelet aggregation is an important process, which is critical for the hemostatic plug formation and thrombosis. Recent studies have shown that the platelet aggregation is more complex and dynamic than it was previously thought. There are several mechanisms that can initiate the platelet aggregation and each of them operates under specific conditions in vivo. At the same time, the influence of certain plasma proteins on this process should be considered. This review intends to summarize the recent data concerning the adhesive molecules and their receptors, which provide the platelet aggregation under different conditions.

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

    Science.gov (United States)

    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

  16. Platelet function studies in women on oral contraceptive pills.

    Science.gov (United States)

    Ishak, R; Mohamed, A B; Hassan, K

    1990-06-01

    A study was conducted on a total of 100 women attending the Family Planning Clinic in Kuala Lumpur. 50 took combined low-dose estrogen and progesterone pills for a year or more and the other 50 used different methods of birth control. Platelet aggregation, ATP release, Thromboxane B2, and 6-keto-prostaglandin F1alpha estimations were made to evaluate the effect of oral contraceptives (OCs) on platelet function and prostanoid production. The results showed no significant differences in the parameters measured in the 2 groups investigated. These findings are comparable to those reported by other studies, suggesting relatively low risk, if any, of thrombosis in OC users.

  17. Evidence of Kinetic Control of Ligand Binding and Staged Product Release in MurA (enolpyruvyl UDP-GlcNAc synthase)-catalyzed Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Jackson, S.; Zhang, F; Chindemi, P; Junop, M; Berti, P

    2009-01-01

    MurA (enolpyruvyl UDP-GlcNAc synthase) catalyzes the first committed step in peptidoglycan biosynthesis. In this study, MurA-catalyzed breakdown of its tetrahedral intermediate (THI), with a k{sub cat}/K{sub M} of 520 M{sup -1} s{sup -1}, was far slower than the normal reaction, and 3 x 10{sup 5}-fold slower than the homologous enzyme, AroA, reacting with its THI. This provided kinetic evidence of slow binding and a conformationally constrained active site. The MurA cocrystal structure with UDP-N-acetylmuramic acid (UDP-MurNAc), a potent inhibitor, and phosphite revealed a new 'staged' MurA conformation in which the Arg397 side chain tracked phosphite out of the catalytic site. The closed-to-staged transition involved breaking eight MurA {center_dot} ligand ion pairs, and three intraprotein hydrogen bonds helping hold the active site loop closed. These were replaced with only two MurA {center_dot} UDP-MurNAc ion pairs, two with phosphite, and seven new intraprotein ion pairs or hydrogen bonds. Cys115 appears to have an important role in forming the staged conformation. The staged conformation appears to be one step in a complex choreography of release of the product from MurA.

  18. Beyond hemostasis: the role of platelets in inflammation, malignancy and infection.

    Science.gov (United States)

    McNicol, Archibald; Israels, Sara J

    2008-06-01

    Platelets play a complex role in hemostasis and thrombosis. The expression of multiple membrane receptors, both constitutive and activation-dependent, mediates platelet adhesion and aggregation at sites of vascular lesion. Platelet activation leads to exocytosis of granular constituents, release of newly synthesized mediators, and discharge of membrane-bound transcellular signaling molecules. Many of the same mechanisms that play a role in hemostasis and thrombosis facilitate platelet participation in other physiological or pathological processes including inflammation, malignancy and the immune response. Platelet receptors such as GPIb/IX/V, P-selectin, P-selectin glycoprotein ligand 1, CD40 and the alphaIIbbeta3 integrin, crucial to hemostasis, have been implicated in the progression of such inflammatory conditions as atherosclerosis, rheumatoid arthritis and inflammatory bowel disease, in the progression and metastatic spread of malignancies, and in the immune response to bacterial challenge. The release of platelet granular contents, including adhesive proteins, growth factors and chemokines/cytokines, that serve to facilitate hemostasis and wound repair, also function in acute and chronic inflammatory disease and in tumor cell activation and growth. Platelets contribute to host defence as they recognise bacteria, recruit traditional immune cells to the site of infection and secrete bactericidal mediators. The primary focus of this review is the "non-haemostatic" functions of platelets in physiological and pathological states.

  19. The hibernating 13-lined ground squirrel as a model organism for potential cold storage of platelets.

    Science.gov (United States)

    Cooper, Scott T; Richters, Karl E; Melin, Travis E; Liu, Zhi-jian; Hordyk, Peter J; Benrud, Ryan R; Geiser, Lauren R; Cash, Steve E; Simon Shelley, C; Howard, David R; Ereth, Mark H; Sola-Visner, Martha C

    2012-05-15

    Hibernating mammals have developed many physiological adaptations to extreme environments. During hibernation, 13-lined ground squirrels (Ictidomys tridecemlineatus) must suppress hemostasis to survive prolonged body temperatures of 4-8°C and 3-5 heartbeats per minute without forming lethal clots. Upon arousal in the spring, these ground squirrels must be able to quickly restore normal clotting activity to avoid bleeding. Here we show that ground squirrel platelets stored in vivo at 4-8°C were released back into the blood within 2 h of arousal in the spring with a body temperature of 37°C but were not rapidly cleared from circulation. These released platelets were capable of forming stable clots and remained in circulation for at least 2 days before newly synthesized platelets were detected. Transfusion of autologous platelets stored at 4°C or 37°C showed the same clearance rates in ground squirrels, whereas rat platelets stored in the cold had a 140-fold increase in clearance rate. Our results demonstrate that ground squirrel platelets appear to be resistant to the platelet cold storage lesions observed in other mammals, allowing prolonged storage in cold stasis and preventing rapid clearance upon spring arousal. Elucidating these adaptations could lead to the development of methods to store human platelets in the cold, extending their shelf life.

  20. Changes in the level of cytosolic calcium, nitric oxide and nitric oxide synthase activity during platelet aggregation: an in vitro study in platelets from normal subjects and those with cirrhosis

    Indian Academy of Sciences (India)

    Sam Annie-JeyachristYn; Arumugam Geetha; Rajagopal Surendran

    2008-03-01

    Variceal bleeding due to abnormal platelet function is a well-known complication of cirrhosis. Nitric oxide-related stress has been implicated in the pathogenesis of liver cirrhosis. In the present investigation, we evaluated the level of platelet aggregation and concomitant changes in the level of platelet cytosolic calcium (Ca2+), nitric oxide (NO) and NO synthase (NOS) activity in liver cirrhosis. The aim of the present study was to investigate whether the production of NO by NOS and level of cytosolic Ca2+ influence the aggregation of platelets in patients with cirrhosis of the liver. Agonist-induced aggregation and the simultaneous changes in the level of cytosolic Ca2+, NO and NOS were monitored in platelets of patients with cirrhosis. Platelet aggregation was also measured in the presence of the eNOS inhibitor, diphenylene iodinium chloride (DIC). The level of agonist-induced platelet aggregation was significantly low in the platelets of patients with cirrhosis compared with that in platelets from normal subjects. During the course of platelet aggregation, concomitant elevation in the level of cytosolic Ca2+ was observed in normal samples, whereas the elevation was not significant in platelets of patients with cirrhosis. A parallel increase was observed in the levels of NO and NOS activity. In the presence of the eNOS inhibitor, platelet aggregation was enhanced and accompanied by an elevated calcium level. The inhibition of platelet aggregation in liver cirrhosis might be partly due to greater NO formation by eNOS. Defective Ca2+ release from the internal stores to the cytosol may account for inhibition of aggregation of platelets in cirrhosis. The NO-related defective aggregation of platelets in patients with cirrhosis found in our study is of clinical importance, and the underlying mechanism of such changes suggests a possible therapeutic strategy with cell-specific NO blockers.

  1. Platelet Concentrates: Past, Present and Future

    OpenAIRE

    2011-01-01

    Platelets play a crucial role in hemostasis and wound healing, platelet growth factors are well known source of healing cytokines. Numerous techniques of autologous platelet concentrates have been developed and applied in oral and maxillofacial surgery. This review describes the evolution of the first and second generation of platelet concentrates (platelet rich plasma and platelet rich fibrin respectively) from their fore runner-fibrin sealants.

  2. Studies on megakaryopoiesis and platelet function

    OpenAIRE

    Meinders, M.

    2015-01-01

    Platelets are blood circulating specialized subcellular fragments, which are produced by megakaryocytes. Platelets are essential for hemostasis and wound healing but also play a role in non-hemostatic processes such as the immune response or cancer metastasis. Considering the immediate precursors of platelets, normal megakaryocyte development is essential for normal platelet function. Although much is known about platelet development, some aspects of platelet production remain poorly understo...

  3. Restoration of responsiveness of phospholipase Cγ2-deficient platelets by enforced expression of phospholipase Cγ1.

    Directory of Open Access Journals (Sweden)

    Yongwei Zheng

    Full Text Available Receptor-mediated platelet activation requires phospholipase C (PLC activity to elevate intracellular calcium and induce actin cytoskeleton reorganization. PLCs are classified into structurally distinct β, γ, δ, ε, ζ, and η isoforms. There are two PLCγ isoforms (PLCγ1, PLCγ2, which are critical for activation by tyrosine kinase-dependent receptors. Platelets express both PLCγ1 and PLCγ2. Although PLCγ2 has been shown to play a dominant role in platelet activation, the extent to which PLCγ1 contributes has not been evaluated. To ascertain the relative contributions of PLCγ1 and PLCγ2 to platelet activation, we generated conditionally PLCγ1-deficient, wild-type (WT, PLCγ2-deficient, and PLCγ1/PLCγ2 double-deficient mice and measured the ability of platelets to respond to different agonists. We found that PLCγ2 deficiency abrogated αIIbβ3-dependent platelet spreading, GPVI-dependent platelet aggregation, and thrombus formation on collagen-coated surfaces under shear conditions, which is dependent on both GPVI and αIIbβ3. Addition of exogenous ADP overcame defective spreading of PLCγ2-deficient platelets on immobilized fibrinogen, suggesting that PLCγ2 is required for granule secretion in response to αIIbβ3 ligation. Consistently, αIIbβ3-mediated release of granule contents was impaired in the absence of PLCγ2. In contrast, PLCγ1-deficient platelets spread and released granule contents normally on fibrinogen, exhibited normal levels of GPVI-dependent aggregation, and formed thrombi normally on collagen-coated surfaces. Interestingly, enforced expression of PLCγ1 fully restored GPVI-dependent aggregation and αIIbβ3-dependent spreading of PLCγ2-deficient platelets. We conclude that platelet activation through GPVI and αIIbβ3 utilizes PLCγ2 because PLCγ1 levels are insufficient to support responsiveness, but that PLCγ1 can restore responsiveness if expressed at levels normally achieved by PLCγ2.

  4. Arachidonic acid metabolism in the platelets and neutrophils of diabetic rabbit and human subjects

    Energy Technology Data Exchange (ETDEWEB)

    Greco, N.J.

    1985-01-01

    An alteration of arachidonic acid metabolism to prostaglandins and leukotrienes from platelets and polymorphonuclear leukocytes respectively is evident in subjects with diabetes mellitus. There is evidence of altered platelet/vascular wall interactions in diabetes mellitus and evidence that polymorphonuclear leukocytes influence the vascular walls. Theories on the pathogenesis of atherosclerosis include both blood cells. Platelet hypersensitivity is evident in those platelets from the alloxan-induced diabetic rabbit either suspended in plasma or buffer. Arachidonic acid- and collagen-induced platelet aggregation, release of /sup 14/serotonin, and T x B/sub 2/ and 12-HETE production is enhanced when responses of diabetic platelets are compared to control platelets. Control rabbit neutrophils produce more LTB/sub 4/, LTB/sub 4/ isomers and 5-HETE than diabetic rabbits neutrophils. Decreased synthesis from diabetic rabbit neutrophils is not explained by increased catabolism of LTB/sub 4/, reesterification of 5-HETE, or increased eicosanoid formation. These experiments demonstrate both platelet and neutrophil dysfunction in diabetic subjects. Because of the involvement of these cells in regulating circulatory homeostatis, abnormal behavior could aggravate the atherosclerotic process. Platelet and neutrophil dysfunctions are noted before macroscopic vascular lesions are apparent suggesting an important role in the pathogenesis of atherosclerosis.

  5. Doxorubicin-loaded platelets as a smart drug delivery system: An improved therapy for lymphoma

    Science.gov (United States)

    Xu, Peipei; Zuo, Huaqin; Chen, Bing; Wang, Ruju; Ahmed, Arsalan; Hu, Yong; Ouyang, Jian

    2017-01-01

    Chemotherapy is majorly used for the treatment of many cancers, including lymphoma. However, cytotoxic drugs, utilized in chemotherapy, can induce various side effects on normal tissues because of their non-specific distribution in the body. Natural platelets are used as drug carriers because of their biocompatibility and specific targeting to vascular disorders, such as cancer, inflammation, and thrombosis. In this work, doxorubicin (DOX) was loaded in natural platelets for treatment of lymphoma. Results showed that DOX was loaded into platelets with high drug loading and encapsulation efficiency. DOX did not significantly induce morphological and functional changes in platelets. DOX-platelet facilitated intracellular drug accumulation through “tumor cell-induced platelet aggregation” and released DOX into the medium in a pH-controlled manner. This phenomenon reduced the adverse effects and enhanced the therapeutic efficacy. The growth inhibition of lymphoma Raji cells was enhanced, and the cardiotoxicity of DOX was reduced when DOX was loaded in platelets. DOX-platelet improved the anti-tumor activity of DOX by regulating the expression of apoptosis-related genes. Thus, platelets can serve as potential drug carriers to deliver DOX for clinical treatment of lymphoma. PMID:28198453

  6. In vivo evidence for platelet-induced physiological angiogenesis by a COX driven mechanism.

    Directory of Open Access Journals (Sweden)

    Ian M Packham

    Full Text Available We sought to determine a role for platelets in in vivo angiogenesis, quantified by changes in the capillary to fibre ratio (C:F of mouse skeletal muscle, utilising two distinct forms of capillary growth to identify differential effects. Capillary sprouting was induced by muscle overload, and longitudinal splitting by chronic hyperaemia. Platelet depletion was achieved by anti-GPIbα antibody treatment. Sprouting induced a significant increase in C:F (1.42±0.02 vs. contralateral 1.29±0.02, P<0.001 that was abolished by platelet depletion, while the significant C:F increase caused by splitting (1.40±0.03 vs. control 1.28±0.03, P<0.01 was unaffected. Granulocyte/monocyte depletion showed this response was not immune-regulated. VEGF overexpression failed to rescue angiogenesis following platelet depletion, suggesting the mechanism is not simply reliant on growth factor release. Sprouting occurred normally following antibody-induced GPVI shedding, suggesting platelet activation via collagen is not involved. BrdU pulse-labelling showed no change in the proliferative potential of cells associated with capillaries after platelet depletion. Inhibition of platelet activation by acetylsalicylic acid abolished sprouting, but not splitting angiogenesis, paralleling the response to platelet depletion. We conclude that platelets differentially regulate mechanisms of angiogenesis in vivo, likely via COX signalling. Since endothelial proliferation is not impaired, we propose a link between COX1 and induction of endothelial migration.

  7. Effects of Pneumolysin on Human Polymorphonuclear Leukocytes and Platelets

    OpenAIRE

    Johnson, M K; Boese-Marrazzo, D; Pierce, W. A.

    1982-01-01

    Pneumolysin was bound by human polymorphonuclear leukocytes in a reaction which occurred very rapidly at 0 degrees C. Low concentrations of pneumolysin were found to stimulate leukocyte migration and lysosomal enzyme secretion. At increasing lysin levels, inhibition of spontaneous migration and chemotaxis, cell death, and lysis were observed. Pneumolysin was also found to lyse platelets and to activate serum to become chemotactic.

  8. Platelet-rich fibrin (PRF): a second-generation platelet concentrate. Part III: leucocyte activation: a new feature for platelet concentrates?

    Science.gov (United States)

    Dohan, David M; Choukroun, Joseph; Diss, Antoine; Dohan, Steve L; Dohan, Anthony J J; Mouhyi, Jaafar; Gogly, Bruno

    2006-03-01

    Platelet-rich fibrin (PRF) belongs to a new generation of platelet concentrates, with simplified processing and without biochemical blood handling. In this third article, we investigate the immune features of this biomaterial. During PRF processing, leucocytes could also secrete cytokines in reaction to the hemostatic and inflammatory phenomena artificially induced in the centrifuged tube. We therefore undertook to quantify 5 significant cell mediators within platelet poor plasma supernatant and PRF clot exudate serum: 3 proinflammatory cytokines (IL-1beta, IL-6, and TNF-alpha), an antiinflammatory cytokine (IL-4), and a key growth promoter of angiogenesis (VEGF). Our data are correlated with that obtained in plasma (nonactivated blood) and in sera (activated blood). These initial analyses revealed that PRF could be an immune regulation node with inflammation retrocontrol abilities. This concept could explain the reduction of postoperative infections when PRF is used as surgical additive.

  9. Platelet-rich fibrin matrix improves wound angiogenesis via inducing endothelial cell proliferation.

    Science.gov (United States)

    Roy, Sashwati; Driggs, Jason; Elgharably, Haytham; Biswas, Sabyasachi; Findley, Muna; Khanna, Savita; Gnyawali, Urmila; Bergdall, Valerie K; Sen, Chandan K

    2011-11-01

    The economic, social, and public health burden of chronic ulcers and other compromised wounds is enormous and rapidly increasing with the aging population. The growth factors derived from platelets play an important role in tissue remodeling including neovascularization. Platelet-rich plasma (PRP) has been utilized and studied for the last four decades. Platelet gel and fibrin sealant, derived from PRP mixed with thrombin and calcium chloride, have been exogenously applied to tissues to promote wound healing, bone growth, hemostasis, and tissue sealing. In this study, we first characterized recovery and viability of as well as growth factor release from platelets in a novel preparation of platelet gel and fibrin matrix, namely platelet-rich fibrin matrix (PRFM). Next, the effect of PRFM application in a delayed model of ischemic wound angiogenesis was investigated. The study, for the first time, shows the kinetics of the viability of platelet-embedded fibrin matrix. A slow and steady release of growth factors from PRFM was observed. The vascular endothelial growth factor released from PRFM was primarily responsible for endothelial mitogenic response via extracellular signal-regulated protein kinase activation pathway. Finally, this preparation of PRFM effectively induced endothelial cell proliferation and improved wound angiogenesis in chronic wounds, providing evidence of probable mechanisms of action of PRFM in healing of chronic ulcers.

  10. Encapsulation of Platelet in Kefiran Polymer and Detection of Bioavailability of Immobilized Platelet in Probiotic Kefiran as A New Drug for Surface Bleeding

    Directory of Open Access Journals (Sweden)

    Anahita Jenab

    2015-11-01

    Full Text Available Background : Kefir contains lactic acid bacteria (Lactobacillus, Lactococcus, Leuconostoc, Acetobacter and Streptococcus and yeasts (Kluyveromyces, Torula, Candida, Saccharomyces .Kefiran is the polysaccharide produced by lactic acid bacteria in kefir.Methods : Kefiran was prepared from milk containing 0.5% fat and 10 grams kefir grains and was separated from kefir by ethanol (0.02 gram following entrapping the platelets to this polymer. Ligand of the platelet-polysaccharide was studied by FTIR.Results : FTIR results showed that the bands of C-O and C-O-C connections were formed and the polysaccharides had been attached to the receptors of the platelet glycoproteins (GP Ib,GPIIb / IIIa. Stability and encapsulation of the platelet and kefiran were assessed by Coulter Counter. Encapsulation of the platelets by polysaccharide at the beginning caused to reduce the number of platelets following by releasing of 50% of the platelets after 3 hours.Conclusion : The platelets were encapsulated in kefiran polymer and detected for bioavailability as new drug for surface bleeding. Also, kefiran has antimicrobial and antifungal properties. On the other hand, the existence of nisin in kefiran could be useful as an antibacterial lantibiotic. 

  11. Differences between mainstream and sidestream tobacco smoke extracts and nicotine in the activation and aggregation of platelets subjected to cardiovascular conditions in diabetes.

    Science.gov (United States)

    Yin, Wei; Rubenstein, David A

    2013-01-01

    Mainstream and sidestream tobacco smoke extracts have been shown to increase platelet activation directly. Furthermore, advanced glycation end products, which are present in the diabetic vasculature, have also been shown to enhance platelet activity. However, the combined effects of these two risk factors on platelet functions remain unclear. Platelets were exposed to tobacco extracts concurrently with advanced glycation end products. Timed samples were removed to assess the extent of platelet activity. The presence of smoke extracts enhanced platelet activity as compared to control conditions, this was especially prevalent for sidestream extracts. With the addition of irreversibly glycated albumin, there was an additive effect, further enhancing platelet responses. This was at least partially regulated by α-granule release and CD41 expression. The combination of cardiovascular risk factors can significantly enhance platelet activation and aggregation, and therefore it is possible to accelerate cardiovascular diseases through the interactions of multiple cardiovascular risk factors.

  12. Cyclic nucleotides and mitogen-activated protein kinases: regulation of simvastatin in platelet activation

    Directory of Open Access Journals (Sweden)

    Hou Ssu-Yu

    2010-06-01

    Full Text Available Abstract Background 3-Hydroxy-3-methyl-glutaryl coenzyme A (HMG-CoA reductase inhibitors (statins have been widely used to reduce cardiovascular risk. These statins (i.e., simvastatin may exert other effects besides from their cholesterol-lowering actions, including inhibition of platelet activation. Platelet activation is relevant to a variety of coronary heart diseases. Although the inhibitory effect of simvastatin in platelet activation has been studied; the detailed signal transductions by which simvastatin inhibit platelet activation has not yet been completely resolved. Methods The aim of this study was to systematically examine the detailed mechanisms of simvastatin in preventing platelet activation. Platelet aggregation, flow cytometric analysis, immunoblotting, and electron spin resonance studies were used to assess the antiplatelet activity of simvastatin. Results Simvastatin (20-50 μM exhibited more-potent activity of inhibiting platelet aggregation stimulated by collagen than other agonists (i.e., thrombin. Simvastatin inhibited collagen-stimulated platelet activation accompanied by [Ca2+]i mobilization, thromboxane A2 (TxA2 formation, and phospholipase C (PLCγ2, protein kinase C (PKC, and mitogen-activated protein kinases (i.e., p38 MAPK, JNKs phosphorylation in washed platelets. Simvastatin obviously increased both cyclic AMP and cyclic GMP levels. Simvastatin markedly increased NO release, vasodilator-stimulated phosphoprotein (VASP phosphorylation, and endothelial nitric oxide synthase (eNOS expression. SQ22536, an inhibitor of adenylate cyclase, markedly reversed the simvastatin-mediated inhibitory effects on platelet aggregation, PLCγ2 and p38 MAPK phosphorylation, and simvastatin-mediated stimulatory effects on VASP and eNOS phosphorylation. Conclusion The most important findings of this study demonstrate for the first time that inhibitory effect of simvastatin in platelet activation may involve activation of the cyclic AMP

  13. Platelet-rich fibrin: a boon in regenerative endodontics.

    Science.gov (United States)

    Rebentish, Priyanka D; Umashetty, Girish; Kaur, Harpreet; Doizode, Trupthi; Kaslekar, Mithun; Chowdhury, Shouvik

    2016-12-01

    Research into regenerative dentistry has contributed momentum to the field of molecular biology. Periapical surgery aims at removing periapical pathology to achieve complete wound healing and regeneration of bone and periodontal tissue. Regenerative endodontic procedures are widely being added to the current armamentarium of pulp therapy procedures. The regenerative potential of platelets has been deliberated. Platelet-rich fibrin (PRF) is a wonderful tissue-engineering product and has recently gained much popularity due its promising results in wound healing bone induction. The features of this product are an attribute of platelets which, after cellular interactions, release growth factors and have shown application in diverse disciplines of dentistry. This paper is intended to shed light onto the various prospects of PRF and to provide clinical insight into regenerative endodontic therapy.

  14. Analyzing the platelet proteome.

    Science.gov (United States)

    García, Angel; Zitzmann, Nicole; Watson, Steve P

    2004-08-01

    During the last 10 years, mass spectrometry (MS) has become a key tool for protein analysis and has underpinned the emerging field of proteomics. Using high-throughput tandem MS/MS following protein separation, it is potentially possible to analyze hundreds to thousands of proteins in a sample at a time. This technology can be used to analyze the protein content (i.e., the proteome) of any cell or tissue and complements the powerful field of genomics. The technology is particularly suitable for platelets because of the absence of a nucleus. Cellular proteins can be separated by either gel-based methods such as two-dimensional gel electrophoresis or one-dimensional sodium dodecyl sulfate polyacrylamide gel electrophoresis followed by liquid chromatography (LC) -MS/MS or by multidimensional LC-MS/MS. Prefractionation techniques, such as subcellular fractionations or immunoprecipitations, can be used to improve the analysis. Each method has particular advantages and disadvantages. Proteomics can be used to compare the proteome of basal and diseased platelets, helping to reveal information on the molecular basis of the disease.

  15. Effects of Nd:YAG laser-heated metal cap on human platelets in vitro

    Science.gov (United States)

    Liu, Xia; Guo, You-chi

    1993-03-01

    Human platelet-rich plasma (PRP) was irradiated in vitro with a fiberoptic Nd:YAG laser-heated metal cap to study its effects on platelets. The energy of the laser was 5 and 10 watts with an irradiation time of 0, 3, 6, and 9 seconds and 14 watts with an irradiation time of 0, 3, 4, and 5 seconds, respectively. The irradiated PRPs were analyzed for platelet count, aggregation reaction, thromboxane (TX)B2 measurement and electron microscopy. Various degrees of decrease in platelet count were observed in all groups. Except the 5Wx3S group, the other groups showed an increase in the maximum aggregation rate of platelets, which corresponded to the enhancement of TXB2 formation. It was also demonstrated by a transmission electron microscopy in 10Wx3S, 10Wx6S, 10Wx9S, 14Wx3S, 14Wx4S, and 14Wx5S energy groups that alpha- and dense-particles in irradiated platelets became sparse in number or even disappeared, less electron density, irregularity in size and shape, and a tendency for these particles to cluster around platelet membranes and open canalicular systems, which dilated apparently. Furthermore, scanning electron microscopy depicted the appearance of short and thick pseudopods on the surfaces of some irradiated platelets and an increase in the axis rate in most of the irradiated platelets.

  16. In vitro effects of mercury on platelet aggregation, thromboxane and vascular prostacyclin production.

    Science.gov (United States)

    Caprino, L; Togna, A R; Cebo, B; Dolci, N; Togna, G

    1983-01-01

    Mercuric chloride [25-50 micrograms/ml platelet-rich plasma (PRP)] lowers the threshold concentration of arachidonic acid (AA) required for triggering rabbit platelet aggregation and causes a marked increase of thromboxane production. The metal, added as HgCl2, does not modify (50 micrograms/ml PRP) or block (100 micrograms/ml PRP) the platelet aggregation wave induced by a normal aggregating dose of AA. Whether or not AA-induced platelet aggregation takes place, a large increase in thromboxane production is observed. Methyl mercury, assayed as reference drug, induces platelet aggregation and a significant increase of thromboxane levels. Finally, HgCl2 and methyl mercury, in a concentration range of 0.125-0.5 micrograms/microliters in the incubation liquid, induce an increased prostacyclin release from rat aortic tissue.

  17. Inflammasome in Platelets: Allying Coagulation and Inflammation in Infectious and Sterile Diseases?

    Directory of Open Access Journals (Sweden)

    Eugenio D. Hottz

    2015-01-01

    Full Text Available Platelets are crucial effector cells in hemostasis. In addition, platelets are increasingly recognized as major inflammatory cells with key roles in innate and adaptive immune responses. Activated platelets have key thromboinflammatory activities linking coagulation to inflammatory response in a variety of coagulation disorders and vasculopathies. Recently identified inflammatory activities of platelets include the synthesis of IL-1β from spliced pre-RNA, as well as the presence and assembly of inflammasome which intermediate IL-1β secretion. Here we review the mechanisms by which platelets activate translation machinery and inflammasome assembly to synthesize and release IL-1β. The contributions of these processes to protective and pathogenic responses during infectious and inflammatory diseases are discussed.

  18. CdTe quantum dots induce activation of human platelets: implications for nanoparticle hemocompatibility

    Science.gov (United States)

    Samuel, Stephen P; Santos-Martinez, Maria J; Medina, Carlos; Jain, Namrata; Radomski, Marek W; Prina-Mello, Adriele; Volkov, Yuri

    2015-01-01

    New nanomaterials intended for systemic administration have raised concerns regarding their biocompatibility and hemocompatibility. Quantum dots (QD) nanoparticles have been used for diagnostics, and recent work suggests their use for in vivo molecular and cellular imaging. However, the hemocompatibility of QDs and their constituent components has not been fully elucidated. In the present study, comprehensive investigation of QD–platelet interactions is presented. These interactions were shown using transmission electron microscopy. The effects of QDs on platelet function were investigated using light aggregometry, quartz crystal microbalance with dissipation, flow cytometry, and gelatin zymography. Platelet morphology was also analyzed by phase-contrast, immunofluorescence, atomic-force and transmission electron microscopy. We show that the QDs bind to platelet plasma membrane with the resultant upregulation of glycoprotein IIb/IIIa and P-selectin receptors, and release of matrix metalloproteinase-2. These findings unravel for the first time the mechanism of functional response of platelets to ultrasmall QDs in vitro. PMID:25897218

  19. Platelet-rich plasma: a biomimetic approach to enhancement of surgical wound healing.

    Science.gov (United States)

    Fernandez-Moure, Joseph S; Van Eps, Jeffrey L; Cabrera, Fernando J; Barbosa, Zonia; Medrano Del Rosal, Guillermo; Weiner, Bradley K; Ellsworth, Warren A; Tasciotti, Ennio

    2017-01-01

    Platelets are small anucleate cytoplasmic cell bodies released by megakaryocytes in response to various physiologic triggers. Traditionally thought to be solely involved in the mechanisms of hemostasis, platelets have gained much attention due to their involvement wound healing, immunomodulation, and antiseptic properties. As the field of surgery continues to evolve so does the need for therapies to aid in treating the increasingly complex patients seen. With over 14 million obstetric, musculoskeletal, and urological and gastrointestinal surgeries performed annually, the healing of surgical wounds continues to be of upmost importance to the surgeon and patient. Platelet-rich plasma, or platelet concentrate, has emerged as a possible adjuvant therapy to aid in the healing of surgical wounds and injuries. In this review, we will discuss the wound healing properties of platelet-rich plasma and various surgical applications. Copyright © 2016 Elsevier Inc. All rights reserved.

  20. The effects of bupivacaine and pipecoloxylidide on platelet function in vitro.

    Science.gov (United States)

    Odoom, J A; Sturk, A; Dokter, P W; Bovill, J G; ten Cate, J W; Oosting, J

    1989-07-01

    The influence of bupivacaine and its major metabolite, pipecoloxylidide, on human platelet function was studied in vitro. Significant inhibition of ADP and collagen-induced platelet aggregation occurred only with concentrations of bupivacaine above 10 micrograms.ml-1. This concentration (10-25 micrograms.ml-1) is much higher than would be expected in routine clinical use of bupivacaine for epidural analgesia. The inhibition of platelet aggregation was associated with a significant decrease in beta-thromboglobulin secretion. In contrast, pipecoloxylidide had no effect on platelet aggregation or the beta-thromboglobulin release. We conclude that the previously reported 30-min time-lag between the maximal plasma concentration of bupivacaine and the inhibition of platelet aggregation is unlikely to be due to a metabolism of bupivacaine to pipecoloxylidide.

  1. Platelet activation during exercise induced asthma: effect of prophylaxis with cromoglycate and salbutamol.

    Science.gov (United States)

    Johnson, C E; Belfield, P W; Davis, S; Cooke, N J; Spencer, A; Davies, J A

    1986-01-01

    Peak expiratory flow (PEF) and plasma concentrations of platelet factor 4 and beta thromboglobulin were measured before and after exercise in nine asthmatic patients and 12 non-asthmatic volunteers. Exercise was preceded by administration in random order of either placebo, salbutamol 200 micrograms, or sodium cromoglycate 2 mg from a pressurised inhaler. In control subjects there were minimal changes in PEF and plasma concentrations of platelet factor 4 and beta thromboglobulin. In the asthmatic patients the typical changes in PEF were seen on exercise; plasma concentrations of platelet factor 4 and beta thromboglobulin rose significantly in parallel, the rise preceding the fall in PEF. The changes in peak flow and platelet activation induced by exercise were attenuated by prior administration of salbutamol or cromoglycate. These results indicate that exercise induced asthma is associated with a rise in platelet release products similar to that observed in antigen induced asthma. PMID:2943049

  2. Inflammasome in Platelets: Allying Coagulation and Inflammation in Infectious and Sterile Diseases?

    Science.gov (United States)

    Hottz, Eugenio D.; Monteiro, Ana Paula T.; Bozza, Fernando A.; Bozza, Patrícia T.

    2015-01-01

    Platelets are crucial effector cells in hemostasis. In addition, platelets are increasingly recognized as major inflammatory cells with key roles in innate and adaptive immune responses. Activated platelets have key thromboinflammatory activities linking coagulation to inflammatory response in a variety of coagulation disorders and vasculopathies. Recently identified inflammatory activities of platelets include the synthesis of IL-1β from spliced pre-RNA, as well as the presence and assembly of inflammasome which intermediate IL-1β secretion. Here we review the mechanisms by which platelets activate translation machinery and inflammasome assembly to synthesize and release IL-1β. The contributions of these processes to protective and pathogenic responses during infectious and inflammatory diseases are discussed. PMID:25814789

  3. Platelet granule exocytosis: A comparison with chromaffin cells

    Directory of Open Access Journals (Sweden)

    Jennifer eFitch-Tewfik

    2013-06-01

    Full Text Available The rapid secretion of bioactive amines from chromaffin cells constitutes an important component of the fight or flight response of mammals to stress. Platelets respond to stresses within the vasculature by rapidly secreting cargo at sites of injury, inflammation, or infection. Although chromaffin cells derive from the neural crest and platelets from bone marrow megakaryocytes, both have evolved a heterogeneous assemblage of granule types and a mechanism for efficient release. This article will provide an overview of granule formation and exocytosis in platelets with an emphasis on areas in which the study of chromaffin cells has influenced that of platelets and on similarities between the two secretory systems. Commonalities include the use of transporters to concentrate bioactive amines and other cargos into granules, the role of cytoskeletal remodeling in granule exocytosis, and the use of granules to provide membrane for cytoplasmic projections. The SNAREs and SNARE accessory proteins used by each cell type will also be considered. Finally, we will discuss the newly appreciated role of dynamin family proteins in regulated fusion pore formation. This evaluation of the comparative cell biology of regulated exocytosis in platelets and chromaffin cells demonstrates a convergence of mechanisms between two disparate cell types both tasked with responding rapidly to physiological stimuli.

  4. Gender, Race, and Diet Affect Platelet Function Tests in Normal Subjects Contributing to a High Rate of Abnormal Results

    OpenAIRE

    Miller, Connie H.; Rice, Anne S.; Garrett, Katherine; Stein, Sidney F.

    2014-01-01

    To assess sources of variability in platelet function tests in normal subjects, 64 healthy young adults were tested on 2–6 occasions at 2 week intervals using 4 methods: platelet aggregation (AGG) in platelet-rich plasma (PRP) in the Bio/Data PAP-4 Aggregometer (BD) and Chrono-Log Lumi-Aggregometer (CL); and AGG in whole blood (WB) in the CL and Multiplate Platelet Function Analyzer (MP), with ATP release (REL) in CL-PRP and CL-WB. Food and medication exposures were recorded prospectively for...

  5. Chemical and structural characterization of a model Post-Termination Complex (PoTC) for the ribosome recycling reaction: Evidence for the release of the mRNA by RRF and EF-G

    Science.gov (United States)

    Iwakura, Nobuhiro; Yokoyama, Takeshi; Quaglia, Fabio; Mitsuoka, Kaoru; Mio, Kazuhiro; Shigematsu, Hideki; Shirouzu, Mikako; Kaji, Akira; Kaji, Hideko

    2017-01-01

    A model Post-Termination Complex (PoTC) used for the discovery of Ribosome Recycling Factor (RRF) was purified and characterized by cryo-electron microscopic analysis and biochemical methods. We established that the model PoTC has mostly one tRNA, at the P/E or P/P position, together with one mRNA. The structural studies were supported by the biochemical measurement of bound tRNA and mRNA. Using this substrate, we establish that the release of tRNA, release of mRNA and splitting of ribosomal subunits occur during the recycling reaction. Order of these events is tRNA release first followed by mRNA release and splitting almost simultaneously. Moreover, we demonstrate that IF3 is not involved in any of the recycling reactions but simply prevents the re-association of split ribosomal subunits. Our finding demonstrates that the important function of RRF includes the release of mRNA, which is often missed by the use of a short ORF with the Shine-Dalgarno sequence near the termination site. PMID:28542628

  6. A recently developed bifacial platelet-rich fibrin matrix.

    Science.gov (United States)

    Lucarelli, E; Beretta, R; Dozza, B; Tazzari, P L; O'Connel, S M; Ricci, F; Pierini, M; Squarzoni, S; Pagliaro, P P; Oprita, E I; Donati, D

    2010-07-01

    Platelet-rich plasma (PRP) is used clinically in liquid or gel form to promote tissue repair. Because of the poor mechanical properties, conventional PRP is often difficult to handle when used in clinical settings and requires secure implantation in a specific site, otherwise when released growth factors could be washed out during an operation. In this study, we analyzed the end product of a recently developed commercially available system (FIBRINET), which is a dense pliable, platelet-rich fibrin matrix (PRFM). We characterized the mechanical properties of PRFM and tested whether PRFM releases growth factors and whether released factors induce the proliferation of mesenchymal stem cells (MSC). Mechanical properties as well as platelet distribution were evaluated in PRFM. PRFM demonstrated robust mechanical properties, with a tear elastic modulus of 937.3 +/- 314.6 kPa, stress at a break of 1476.0 +/- 526.3 kPa, and an elongation at break of 146.3 +/- 33.8 %. PRFM maintained its mechanical properties throughout the testing process. Microscopic observations showed that the platelets were localized on one side of the matrix. Elevated levels of PDGF-AA, PDGF-AB, EGF, VEGF, bFGF and TGF-beta1 were measured in the day 1-conditioned media (CM) of PRFM and growth factor levels decreased thereafter. BMP2 and BMP7 were not detectable. MSC culture media supplemented with 20% PRFM-CM stimulated MSC cell proliferation; at 24 and 48 hours the induction of the proliferation was significantly greater than the induction obtained with media supplemented with 20% foetal bovine serum. The present study shows that the production of a dense, physically robust PRFM made through high-speed centrifugation of intact platelets and fibrin in the absence of exogenous thrombin yields a potential tool for accelerating tissue repair.

  7. A recently developed bifacial platelet-rich fibrin matrix

    Directory of Open Access Journals (Sweden)

    E Lucarelli

    2010-07-01

    Full Text Available Platelet-rich plasma (PRP is used clinically in liquid or gel form to promote tissue repair. Because of the poor mechanical properties, conventional PRP is often difficult to handle when used in clinical settings and requires secure implantation in a specific site, otherwise when released growth factors could be washed out during an operation. In this study, we analyzed the end product of a recently developed commercially available system (FIBRINET®, which is a dense pliable, platelet-rich fibrin matrix (PRFM. We characterized the mechanical properties of PRFM and tested whether PRFM releases growth factors and whether released factors induce the proliferation of mesenchymal stem cells (MSC. Mechanical properties as well as platelet distribution were evaluated in PRFM. PRFM demonstrated robust mechanical properties, with a tear elastic modulus of 937.3 + 314.6 kPa, stress at a break of 1476.0 + 526.3 kPa, and an elongation at break of 146.3 + 33.8 %. PRFM maintained its mechanical properties throughout the testing process. Microscopic observations showed that the platelets were localized on one side of the matrix. Elevated levels of PDGF-AA, PDGF-AB, EGF, VEGF, bFGF and TGF-β1 were measured in the day 1-conditioned media (CM of PRFM and growth factor levels decreased thereafter. BMP2 and BMP7 were not detectable. MSC culture media supplemented with 20% PRFM-CM stimulated MSC cell proliferation; at 24 and 48 hours the induction of the proliferation was significantly greater than the induction obtained with media supplemented with 20% foetal bovine serum. The present study shows that the production of a dense, physically robust PRFM made through high-speed centrifugation of intact platelets and fibrin in the absence of exogenous thrombin yields a potential tool for accelerating tissue repair.

  8. Platelet rich fibrin and xenograft in treatment of intrabony defect

    Directory of Open Access Journals (Sweden)

    Saurav Panda

    2014-01-01

    Full Text Available For complete periodontal regeneration, delivery of growth factors in the local environment holds a great deal in adjunct to bone grafts. Platelet rich fibrin (PRF is considered as second generation platelet concentrate, consisting of viable platelets, releasing various growth factors such as platelet-derived growth factor, vascular endothelial growth factor, transforming growth factor, insulin-like growth factor, epidermal growth factor and basic fibroblast growth factor. Hence, this case report aims to investigate the clinical and radiological (bone fill effectiveness of autologous PRF along with the use of xenogenic bone mineral in the treatment of intra bony defects. Intrabony defect was treated with autologous PRF along with the use of xenogenic bone mineral. A decrease in probing pocket depth, gain in clinical attachment level and significant bone fill was observed at end of 6 months. The result obtained with the use of PRF may be attributed to the sustained and simultaneous release of various growth factors over a period of 7 days. In this case report, the positive clinical impact of additional application of PRF with xenogenic graft material in the treatment of periodontal intrabony defect was seen.

  9. Treatment of chronic venous leg ulcers by platelet gel.

    Science.gov (United States)

    Ficarelli, Elena; Bernuzzi, Gino; Tognetti, Elena; Bussolati, Ovidio; Zucchi, Alfredo; Adorni, Daniela; De Panfilis, Giuseppe

    2008-07-01

    Chronic venous leg ulcers (CVLU) are chronic wounds, associated with long-standing venous hypertension, which have a poor prognosis for healing. In the process of wound healing the first step is represented by platelet aggregation and subsequent release of growth factors and other mediators, which play a key role in the repair response. Platelet gel (PG), a hemocomponent obtained by mixing platelets, thrombin, and calcium, is able, when applied topically, to release platelet mediators that likely favor CVLU healing. However, unstandardized protocols have been described in studies utilizing PG for the regeneration of a number of tissues, including CVLU; the relative clinical outcomes were hence highly variable. In our experience the topical use of PG, together with the strict adherence to the principles of good wound care, quickly promoted increased granulation tissue, followed by a complete CVLU epithelization. Although further studies and trials are needed to establish the major outcome affecting rules for optimal indications, preparation, and use of PG for CVLU treatment, PG can be undoubtedly considered a useful tool, able to improve the management of CVLU.

  10. Platelets in inflammation and infection.

    Science.gov (United States)

    Jenne, Craig N; Kubes, Paul

    2015-01-01

    Although platelets are traditionally recognized for their central role in hemostasis, many lines of research clearly demonstrate these rather ubiquitous blood components are potent immune modulators and effectors. Platelets have been shown to directly recognize, sequester and kill pathogens, to activated and recruit leukocytes to sites of infection and inflammation, and to modulate leukocyte behavior, enhancing their ability to phagocytose and kill pathogens and inducing unique effector functions, such as the production of Neutrophil Extracellular Traps (NETs). This multifaceted response to infection and inflammation is due, in part, to the huge array of soluble mediators and cell surface molecules expressed by platelets. From their earliest origins as primordial hemocytes in invertebrates to their current form as megakaryocyte-derived cytoplasts, platelets have evolved to be one of the key regulators of host intravascular immunity and inflammation. In this review, we present the diverse roles platelets play in immunity and inflammation associated with autoimmune diseases and infection. Additionally, we highlight recent advances in our understanding of platelet behavior made possible through the use of advanced imaging techniques that allow us to visualize platelets and their interactions, in real-time, within the intact blood vessels of a living host.

  11. [Murine models of platelet diseases].

    Science.gov (United States)

    Lanza, F

    2007-05-01

    Platelet-related diseases correspond to functional defects or abnormal production (thrombopoiesis) of hereditary and immunological origins. Recent progress in the manipulation of the mouse genome (transgenesis, gene inactivation or insertion) has resulted in the generation of numerous strains exhibiting defective platelet function or production. Some strains reproduce known hereditary diseases affecting haemostasis (Glanzmann thrombasthenia, Bernard-Soulier syndrome (BSS) or thrombopoiesis (Wiscott-Aldrich or May-Hegglin syndrome). More often the mutated strains have no human equivalent and represent useful models to study: (i) the role of adhesive or signalling receptors or of signalling proteins in platelet-dependent haemostasis and thrombosis or; (ii) to study the poorly characterized mechanisms of thrombopoiesis, which implicate transcription factors (GATA, Fli1), growth factors and receptors (TPO, cMPL), and cytoskeletal or contractile proteins (tubulin, myosin). Additional mouse strains result from the selection of spontaneous mutants many of which affect intracellular platelet granules, representing models of storage pool diseases (SPD) such as the Gray platelet syndrome (alphaSPD) or Hermansky-Pudlack syndrome (deltaSPD). More recently, a systematic chemical mutagenesis approach has also identified genes involved in thrombopoiesis and platelet survival. Finally, mouse models of auto- or allo-immune thrombocytopenia have been developed to study the mechanisms of platelet destruction or removal.

  12. Platelet scintigraphy in atherothrombotic disease

    Energy Technology Data Exchange (ETDEWEB)

    Isaka, Yoshinari (Osaka National Hospital (Japan))

    1993-01-01

    Indium-111 platelet scintigraphy for the measurement of in vivo thrombogenicity is a useful noninvasive technique with a number of applications. From 1982 to 1989, we explored clinical relevance of this method for 576 consecutive patients with atherothrombotic disease. There was a disease-related difference in the percentage of positive platelet accumulation; 85% in patients with Dacron bifurcation graft, 75% in abdominal or thoracic aneurysm, 40% in intra-cardiac thrombi, 33% in arteriosclerosis obliterans and 25% in ischemic cerebrovascular disease. Labelled platelets accumulated frequently in the lesion with severe arteriographic abnormality. Aspirin clearly inhibited platelet accumulation on carotid atheroma but the effect of ticlopidine has been less conclusive. Short-term orally active PGI[sub 2] analogue had inhibitory effects on platelet accumulation in carotid atheroma and platelet aggregability, but did not cause significant reduction in plaque size. The results suggest the usefulness of platelet scintigraphy for monitoring the thrombogenicity in various atherothrombotic diseases. It will be necessary, however, to simplify the labelling procedures and to develop a new [sup 99m]Tc-labelled thrombus imaging agent, if thrombus imaging is to be considered for more generall use for patients with atherosclerosis. (author).

  13. Contribution of blood platelets to vascular pathology in Alzheimer's disease

    Directory of Open Access Journals (Sweden)

    Zhang W

    2013-11-01

    Full Text Available Wei Zhang,1,2 Wei Huang,1 Fang Jing11Department of Pharmacology, Institutes for Advanced Interdisciplinary Research, East China Normal University, Shanghai, People's Republic of China; 2Shanghai Engineering Research Center of Molecular Therapy and Pharmaceutical Innovation, Shanghai, People's Republic of ChinaAbstract: Cerebral amyloid angiopathy (CAA is a critical factor in the pathogenesis of Alzheimer's disease (AD. In the clinical setting, nearly 98% AD patients have CAA, and 75% of these patients are rated as severe CAA. It is characterized by the deposition of the β-amyloid peptide (mainly Aβ40 in the walls of cerebral vessels, which induces the degeneration of vessel wall components, reduces cerebral blood flow, and aggravates cognitive decline. Platelets are anuclear cell fragments from bone marrow megakaryocytes and their function in hemostasis and thrombosis has long been recognized. Recently, increasing evidence suggests that platelet activation can also mediate the onset and development of CAA. First, platelet activation and adhesion to a vessel wall is the initial step of vascular injury. Activated platelets contribute to more than 90% circulating Aß (mainly Aβ1-40, which in turn activates platelets and results in the vicious cycle of Aβ overproduction in damaged vessel. Second, the uncontrolled activation of platelets leads to a chronic inflammatory reaction by secretion of chemokines (eg, platelet factor 4 [PF4], regulated upon activation normal T-cell expressed and presumably secreted [RANTES], and macrophage inflammatory protein [MIP-1α], interleukins (IL-1 β, IL-7, and IL-8, prostaglandins, and CD40 ligand (CD40L. The interaction of these biological response modulators with platelets, endothelial cells, and leukocytes establishes a localized inflammatory response that contributes to CAA formation. Finally, activated platelets are the upholder of fibrin clots, which are structurally abnormal and resistant to degradation

  14. Platelet enzyme abnormalities in leukemias

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    S Sharma

    2011-01-01

    Full Text Available Aim of the Study: The aim of this study was to evaluate platelet enzyme activity in cases of leukemia. Materials and Methods: Platelet enzymes glucose-6-phosphate dehydrogenase (G6PD, pyruvate kinase (PK and hexokinase (HK were studied in 47 patients of acute and chronic leukemia patients, 16 patients with acute myeloid leukemia (AML(13 relapse, three in remission, 12 patients with acute lymphocytic leukemia (ALL (five in relapse, seven in remission, 19 patients with chronic myeloid leukemia (CML. Results: The platelet G6PD activity was significantly low in cases of AML, ALL and also in CML. G6PD activity was normalized during AML remission. G6PD activity, although persistently low during ALL remission, increased significantly to near-normal during remission (P < 0.05 as compared with relapse (P < 0.01. Platelet PK activity was high during AML relapse (P < 0.05, which was normalized during remission. Platelet HK however was found to be decreased during all remission (P < 0.05. There was a significant positive correlation between G6PD and PK in cases of AML (P < 0.001 but not in ALL and CML. G6PD activity did not correlate with HK activity in any of the leukemic groups. A significant positive correlation was however seen between PK and HK activity in cases of ALL remission (P < 0.01 and CML (P < 0.05. Conclusions: Both red cell and platelet enzymes were studied in 36 leukemic patients and there was no statistically significant correlation between red cell and platelet enzymes. Platelet enzyme defect in leukemias suggests the inherent abnormality in megakaryopoiesis and would explain the functional platelet defects in leukemias.

  15. Anti-platelet antibodies in a natural animal model of sulphonamide-associated thrombocytopaenia.

    Science.gov (United States)

    Lavergne, Sidonie N; Trepanier, Lauren A

    2007-12-01

    Delayed hypersensitivity (HS) reactions to sulphonamide antimicrobials occur in both humans and dogs with a similar clinical presentation, and may include thrombocytopaenia. Drug-dependent anti-platelet antibodies have been identified in humans with sulphonamide-associated thrombocytopaenia. Our purpose was to determine whether similar antibodies were present in dogs with sulphonamide-associated thrombocytopaenia. Flow cytometry was used to detect anti-platelet antibodies in sera from 32 dogs with sulphonamide HS, eight dogs that tolerated sulphonamide therapy without adverse reactions and nine healthy control dogs were used as controls. Anti-platelet antibodies were found more frequently, with significantly stronger fluorescence signals, in HS dogs (75%) compared to 'tolerant' dogs (38%), and in HS dogs with thrombocytopaenia (90%) compared to HS dogs with normal platelet counts (46%). Binding to platelets was enhanced in the presence of soluble sulphonamide in 42% of positive samples. Experiments with canine Glanzmann's platelets, and competition assays with fibrinogen fragments or anti-GP antibodies, did not support the hypothesis that these canine antibodies target the fibrinogen receptor. In conclusion, anti-platelet antibodies were identified in dogs with sulphonamide-associated thrombocytopaenia, which suggests a similar immunopathogenesis for this reaction in dogs as seen in humans. Further work in both species will determine whether these antibodies are pathogenic in vitro.

  16. Platelet surface glutathione reductase-like activity.

    Science.gov (United States)

    Essex, David W; Li, Mengru; Feinman, Richard D; Miller, Anna

    2004-09-01

    We previously found that reduced glutathione (GSH) or a mixture of GSH/glutathione disulfide (GSSG) potentiated platelet aggregation. We here report that GSSG, when added to platelets alone, also potentiates platelet aggregation. Most of the GSSG was converted to GSH by a flavoprotein-dependent platelet surface mechanism. This provided an appropriate redox potential for platelet activation. The addition of GSSG to platelets generated sulfhydryls in the beta subunit of the alpha(IIb)beta(3) fibrinogen receptor, suggesting a mechanism for facilitation of agonist-induced platelet activation.

  17. Revascularization of Immature Necrotic Teeth: Platelet rich Fibrin an Edge over Platelet rich Plasma

    Directory of Open Access Journals (Sweden)

    Neelam Mittal

    2012-03-01

    Full Text Available Introduction: Revascularization is one such entity that has found its clinical application in the field of endodontics for the manage-ment of immature permanent necrotic teeth. The protocols for revascularization of such teeth focus especially on delivery of stem cells and scaffolds in a nonsurgical manner rather than concentrated growth micro molecules.The hypothesis: This article proposes the role of platelet concentrates such as platelet rich fibrin (PRF and platelet rich plasma (PRP in accelerating the regenerative process in such teeth. PRF unlike PRP is associated with slow, continuous and substantial re-lease of morphogens. It is hypothesized further if PRF instead of PRP when placed through immature apices in an orthograde manner can open newer gates for fast and controlled growth in young, ne-crotic, non-infected teeth.Evaluation of the hypothesis: Enhancement of the healing kinetics can be evaluated by change in size of periapical radiolucency, thickness of the dentinal walls, root elongation and apical closure compared between preoperative and postoperative standardized two dimensional/three dimensional radiographs taken on regular follow ups.

  18. The association of thromboxane A2 receptor with lipid rafts is a determinant for platelet functional responses.

    Science.gov (United States)

    Moscardó, A; Vallés, J; Latorre, A; Santos, M T

    2014-08-25

    We have investigated the presence of thromboxane A2 (TXA2) receptor associated with lipid rafts in human platelets and the regulation of platelet function in response to TXA2 receptor agonists when lipid rafts are disrupted by cholesterol extraction. Platelet aggregation with TXA2 analogs U46619 and IBOP was almost blunted in cholesterol-depleted platelets, as well as αIIbβ3 integrin activation and P-selectin exposure. Raft disruption also inhibited TXA2-induced cytosolic calcium increase and nucleotide release, ruling out an implication of P2Y12 receptor. An important proportion of TXA2 receptor (40%) was colocalized at lipid rafts. The presence of the TXA2 receptor associated with lipid rafts in platelets is important for functional platelet responses to TXA2.

  19. Extract of a spice--omum (Trachyspermum ammi)-shows antiaggregatory effects and alters arachidonic acid metabolism in human platelets.

    Science.gov (United States)

    Srivastava, K C

    1988-07-01

    An ethereal extract of omum (Trachyspermum ammi; Hindustani: ajwan)--a frequently consumed spice--was found to inhibit platelet aggregation induced by arachidonic acid (AA), epinephrine and collagen; in this respect it was most effective against AA-induced aggregation. Inhibition of aggregation by omum could be explained by its effect on platelet thromboxane production as suggested by the following experimental observation. (i) Omum reduced TxB2 formation in intact platelet preparations from added arachidonate, and (ii) it reduced the formation of TxB2 from AA-labelled platelets after stimulation with Ca2+-ionophore A23187 by a direct action on cyclooxygenase as it did not affect the release of AA from labelled platelets. An increased formation of lipoxygenase-derived products from exogenous AA in omum-treated platelets was apparently due to redirection of AA from cyclooxygenase to the lipoxygenase pathway.

  20. Platelet P2Y12 is involved in murine pulmonary metastasis.

    Directory of Open Access Journals (Sweden)

    Yanhua Wang

    Full Text Available The involvement of platelets in tumor progression is well recognized. The depletion of circulating platelets or pharmacologic inhibitors of platelet activation decreases the metastatic potential of circulating tumor cells in metastasis mouse models. The platelet ADP receptor P2Y12 amplifies the initial hemostatic responses activated by a variety of platelet agonists and stabilizes platelet aggregation, playing a crucial role in granule secretion, integrin activation and thrombus formation. However, the relationship between P2Y12 and tumor progression is not clear. In our study, the Lewis Lung Carcinoma (LLC spontaneous metastatic mouse model was used to evaluate the role of P2Y12 in metastasis. The results demonstrated that P2Y12 deficiency significantly reduced pulmonary metastasis. Further studies indicated that P2Y12 deficiency diminished the ability of LLC cells to induce platelet shape change and release of active TGFβ1 by a non-contact dependent mechanism resulting in a diminished, platelet-induced EMT-like transformation of the LLC cells, and that transformation probably is a prerequisite of LLC cell metastasis. Immunohistochemical analyses indicated an obvious P2Y12 deficiency related attenuation of recruitment of VEGFR1+ bone marrow derived cell clusters, and extracellular matrix fibronectin deposition in lungs, which presumably are required for pre-metastatic niche formation. In contrast to the LLC cells, non-epithelial melanoma B16 cells induced platelet aggregation in a cell number and P2Y12-dependent manner. Also, a platelet induced EMT-like transformation of B16 cells is dependent on P2Y12. In agreement with the LLC cell model, platelet P2Y12 deficiency also results in significantly less lung metastasis in the B16 melanoma experimental metastasis model. These results demonstrate that P2Y12 is a safe drug target for anti-thrombotic therapy, and that P2Y12 may serve as a new target for inhibition of tumor metastasis.

  1. [Application of platelet rich plasma (PRP) and its derivatives in dental implantologie and plastic surgery].

    Science.gov (United States)

    González, Maczy; Arteaga-Vizcaíno, Melvis; Benito, Marisol; Benito, Mariluz

    2012-12-01

    The platelet rich plasma (PRP), as its name implies, has a high concentration of thrombocytes; is a non-toxic and non-allergenic autologous preparation, obtained by blood centrifugation at low speed. Its function is directly linked to the release of growth factors (FC) by platelets. These factors have properties of induction of tissue regeneration. For the preparation of the present work, a literature search was performed in different documentary sources using the following descriptors: platelet rich plasma, PRP, growth factors, GF, dentistry and cosmetic surgery. This article is a description of some relevant aspects of the PRP and its application in the areas of dentistry and cosmetic surgery.

  2. 富血小板纤维蛋白体外释放TGF-β和PDGF-AB影响因素的探讨%Investigation of effect factors of TGF-β and PDGF-AB levels in platelet-rich fibrin releasing in vitro

    Institute of Scientific and Technical Information of China (English)

    李艳秋; 周延民; 孙晓琳; 张天首; 朱婷

    2012-01-01

    目的 探讨不同方法对制备的富血小板纤维蛋白(platelet-rich fibrin,PRF)释放生长因子的影响.方法 对志愿者进行静脉采血,分别以不同离心速度(2500r/min、3000r/min、3500r/min)、离心时间(10min、15min、20min)和除水方法(快速除水和缓慢除水)制备PRF,收集PRF所释放的生长因子,通过ELISA法比较不同方法所获得的PRF释放的TGF-β和PDGF-AB的浓度差异.结果 以3000r/min的离心速度制备的PRF释放TGF-β和PDGF-AB含量显著高于其他两组;10min组和15min组制备的PRF释放TGF-β含量高于20min组,而PDGF-AB含量10min组显著高于其他两组;两种除水方法制备的PRF释放TGF-β和PDGF-AB含量无统计学差异(P>0.05).结论 不同离心速度、离心时间对PRF的特性存在一定的影响,而快速除水和缓慢除水对PRF特性的影响无显著性差异.%Objective To investigate the influence factors of platelet-rich fibrin releasing growth factors with different kinds. Methods PRF were produced by different centrifugal speed (2500r/min、3000r/min、3500r/min) , centrifugal time (10min、15min、20min) and dehydration methods (fast dehydration methods and slow dehydration methods) from volunteers.Collect the growth factors in PRF ,and Compare the TGF-β and PDGF-AB concentration by ELISA. Results TGF-pand PDGF-AB levels in the PRF prepared by 3000r/min were higher ; TGF-filevel in the PRF prepared by 10min and 15min were higher, and PDGF-AB level in the PRF prepared by 10min were higher;but the two dehydration methods showed no statistics significance (R>0.05). Conclusion Different centrifugal speed and centrifugal time may affect the characteristics of PRF, and dehydration methods may not affect the characteristics of PRF.

  3. Mechanisms of platelet-mediated liver regeneration.

    Science.gov (United States)

    Lisman, Ton; Porte, Robert J

    2016-08-04

    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.

  4. Probing the kinetic energy-release dynamics of H-atom products from the gas-phase reaction of O(3P) with vinyl radical C2H3.

    Science.gov (United States)

    Jang, Su-Chan; Choi, Jong-Ho

    2014-11-21

    The gas-phase radical-radical reaction dynamics of ground-state atomic oxygen O((3)P) with vinyl radicals C2H3 has been studied by combining the results of vacuum-ultraviolet laser-induced fluorescence spectroscopy in a crossed beam configuration with ab initio calculations. The two radical reactants O((3)P) and C2H3 were produced by photolysis of NO2 and supersonic flash pyrolysis of C2H3I, respectively. Doppler profile analysis of the kinetic energy release of the nascent H-atom products from the title reaction O((3)P) + C2H3→ H((2)S) + CH2CO (ketene) revealed that the average translational energy of the products and the average fraction of the total available energy were 7.03 ± 0.30 kcal mol(-1) and 7.2%. The empirical data combined with CBS-QB3 level ab initio theory and statistical calculations demonstrated that the title oxygen-hydrogen exchange reaction is a major reaction channel, through an addition-elimination mechanism involving the formation of a short-lived, dynamical complex on the doublet potential energy surface. On the basis of systematic comparison with several exchange reactions of hydrocarbon radicals, the observed kinetic energy release can be explained in terms of the weak impulse at the moment of decomposition in the loose transition state with a product-like geometry and a small reverse barrier along the exit channel.

  5. Gray platelet syndrome and defective thrombo-inflammation in Nbeal2-deficient mice.

    Science.gov (United States)

    Deppermann, Carsten; Cherpokova, Deya; Nurden, Paquita; Schulz, Jan-Niklas; Thielmann, Ina; Kraft, Peter; Vögtle, Timo; Kleinschnitz, Christoph; Dütting, Sebastian; Krohne, Georg; Eming, Sabine A; Nurden, Alan T; Eckes, Beate; Stoll, Guido; Stegner, David; Nieswandt, Bernhard

    2013-07-01

    Platelets are anuclear organelle-rich cell fragments derived from bone marrow megakaryocytes (MKs) that safeguard vascular integrity. The major platelet organelles, α-granules, release proteins that participate in thrombus formation and hemostasis. Proteins stored in α-granules are also thought to play a role in inflammation and wound healing, but their functional significance in vivo is unknown. Mutations in NBEAL2 have been linked to gray platelet syndrome (GPS), a rare bleeding disorder characterized by macrothrombocytopenia, with platelets lacking α-granules. Here we show that Nbeal2-knockout mice display the characteristics of human GPS, with defective α-granule biogenesis in MKs and their absence from platelets. Nbeal2 deficiency did not affect MK differentiation and proplatelet formation in vitro or platelet life span in vivo. Nbeal2-deficient platelets displayed impaired adhesion, aggregation, and coagulant activity ex vivo that translated into defective arterial thrombus formation and protection from thrombo-inflammatory brain infarction following focal cerebral ischemia. In a model of excisional skin wound repair, Nbeal2-deficient mice exhibited impaired development of functional granulation tissue due to severely reduced differentiation of myofibroblasts in the absence of α-granule secretion. This study demonstrates that platelet α-granule constituents are critically required not only for hemostasis but also thrombosis, acute thrombo-inflammatory disease states, and tissue reconstitution after injury.

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

    Science.gov (United States)

    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.

  7. Platelet adhesion studies on nanostructured poly(lactic-co-glycolic-acid)-carbon nanotube composite.

    Science.gov (United States)

    Koh, Li Buay; Rodriguez, Isabel; Zhou, Jijie

    2008-08-01

    Design of blood-compatible surfaces is required to minimize platelet-surface interactions and increase the thromboresistance of foreign surfaces. Poly(lactic-co-glycolic-acid)-carbon nanotube (PLGA-CNT) composite is studied as a building material to fabricate artificial blood prostheses. This nanocomposite-based biomaterial is prepared by an electrostatic Layer-by-Layer (LbL) deposition technique, in which layers of CNTs are adsorbed onto a PLGA film. Before incubation in nonstimulated platelet-rich plasma (PRP) for platelet studies, fibrinogen is immobilized on PLGA-CNT composite. Interactions between the plasma proteins, e.g. fibrinogen and PRP, are investigated on the prepared PLGA-CNT composite. Contact angle measurements on the PLGA-CNT composite displayed a good resistance of platelets adhesion on a hydrophilic surface with an angle of 64.94 degrees as compared to pristine PLGA control with an angle of 93.43 degrees . A significant reduction of adhesion is observed on the PLGA-CNT composite, as well as the absence of platelet activation. On the contrary, both platelet adhesion and activation are observed on control samples. We inferred this suppression in secretion of granule contents in the platelet by the presence of the CNTs that resulted in the absence of platelet activation and its subsequent inhibition in the release of adhesive membrane receptors on the PLGA-CNT composite.

  8. Identification of potential platelet alloantigens in the Equidae family by comparison of gene sequences encoding major platelet membrane glycoproteins.

    Science.gov (United States)

    Boudreaux, Mary K; Humphries, Drew M

    2013-12-01

    Platelet alloantigens in horses may play an important role in the development of neonatal alloimmune thrombocytopenia (NAIT). The objective of this study was to evaluate genes encoding major platelet glycoproteins within the Equidae family in an effort to identify potential alloantigens. DNA was isolated from blood samples obtained from Equidae family members, including a Holsteiner-Oldenburg cross, a Quarter horse, a donkey, and a Plains zebra (Equus burchelli). Gene sequences encoding equine platelet membrane glycoproteins IIb, IIIa (integrin subunits αIIb and β3), Ia (integrin subunit α2), and Ibα were determined using PCR. Gene sequences were compared to the equine genome available on GenBank. Polymorphisms that would be predicted to result in amino acid changes on platelet surfaces were documented and compared with known alloantigenic sites documented on human platelets. Amino acid differences were predicted based on nucleotide sequences for all 4 genes. Nine differences were documented for αIIb, 5 differences were documented for β3, 7 differences were documented for α2, and 16 differences were documented for Ibα outside the macroglycopeptide region. This study represents the first effort at identifying potential platelet alloantigens in members of the Equidae Family based on evaluation of gene sequences. The data obtained form the groundwork for identifying potential platelet alloantigens involved in transfusion reactions and neonatal alloimmune thrombocytopenia (NAIT). More work is required to determine whether the predicted amino acid differences documented in this study play a role in alloimmunity, and whether other polymorphisms not detected in this study are present that may result in alloimmunity. © 2013 American Society for Veterinary Clinical Pathology.

  9. In vitro and in vivo characterization of ultraviolet light C-irradiated human platelets in a 2 event mouse model of transfusion.

    Directory of Open Access Journals (Sweden)

    Li Zhi

    Full Text Available UV-based pathogen reduction technologies have been developed in recent years to inactivate pathogens and contaminating leukocytes in platelet transfusion products in order to prevent transfusion-transmitted infections and alloimmunization. UVC-based technology differs from UVA or UVB-based technologies in that it uses a specific wavelength at 254 nm without the addition of any photosensitizers. Previously, it was reported that UVC irradiation induces platelet aggregation and activation. To understand if UVC-induced changes of platelet quality correlate with potential adverse events when these platelets are transfused into animals, we used a 2-event SCID mouse model in which the predisposing event was LPS treatment and the second event was infusion of UVC-irradiated platelets. We analyzed lung platelet accumulation, protein content in bronchoalveolar lavage fluid as an indication of lung injury, and macrophage inflammatory protein-2 (MIP-2 release in mice received UVC-irradiated or untreated control platelets. Our results showed UVC-irradiated platelets accumulated in lungs of the mice in a dose-dependent manner. High-doses of UVC-irradiated platelets were sequestered in the lungs to a similar level as we previously reported for UVB-irradiated platelets. Unlike UVB-platelets, UVC-platelets did not lead to lung injury or induce MIP-2 release. This could potentially be explained by our observation that although UVC treatment activated platelet surface αIIbβ3, it failed to activate platelet cells. It also suggests lung platelet accumulation and subsequent lung damage are due to different and separate mechanisms which require further investigation.

  10. In vitro and in vivo characterization of ultraviolet light C-irradiated human platelets in a 2 event mouse model of transfusion.

    Science.gov (United States)

    Zhi, Li; Chi, Xuan; Vostal, Jaroslav G

    2013-01-01

    UV-based pathogen reduction technologies have been developed in recent years to inactivate pathogens and contaminating leukocytes in platelet transfusion products in order to prevent transfusion-transmitted infections and alloimmunization. UVC-based technology differs from UVA or UVB-based technologies in that it uses a specific wavelength at 254 nm without the addition of any photosensitizers. Previously, it was reported that UVC irradiation induces platelet aggregation and activation. To understand if UVC-induced changes of platelet quality correlate with potential adverse events when these platelets are transfused into animals, we used a 2-event SCID mouse model in which the predisposing event was LPS treatment and the second event was infusion of UVC-irradiated platelets. We analyzed lung platelet accumulation, protein content in bronchoalveolar lavage fluid as an indication of lung injury, and macrophage inflammatory protein-2 (MIP-2) release in mice received UVC-irradiated or untreated control platelets. Our results showed UVC-irradiated platelets accumulated in lungs of the mice in a dose-dependent manner. High-doses of UVC-irradiated platelets were sequestered in the lungs to a similar level as we previously reported for UVB-irradiated platelets. Unlike UVB-platelets, UVC-platelets did not lead to lung injury or induce MIP-2 release. This could potentially be explained by our observation that although UVC treatment activated platelet surface αIIbβ3, it failed to activate platelet cells. It also suggests lung platelet accumulation and subsequent lung damage are due to different and separate mechanisms which require further investigation.

  11. [Protein kinase C activation induces platelet apoptosis].

    Science.gov (United States)

    Zhao, Li-Li; Chen, Meng-Xing; Zhang, Ming-Yi; Dai, Ke-Sheng

    2013-10-01

    Platelet apoptosis elucidated by either physical or chemical compound or platelet storage occurs wildly, which might play important roles in controlling the numbers and functions of circulated platelets, or in the development of some platelet-related diseases. However, up to now, a little is known about the regulatory mechanisms of platelet apoptosis. Protein kinase C (PKC) is highly expressed in platelets and plays central roles in regulating platelet functions. Although there is evidence indicating that PKC is involved in the regulation of apoptosis of nucleated cells, it is still unclear whether PKC plays a role in platelet apoptosis. The aim of this study was to investigate the role of PKC in platelet apoptosis. The effects of PKC on mitochondrial membrane potential (ΔΨm), phosphatidylserine (PS) exposure, and caspase-3 activation of platelets were analyzed by flow cytometry and Western blot. The results showed that the ΔΨm depolarization in platelets was induced by PKC activator in time-dependent manner, and the caspase-3 activation in platelets was induced by PKC in concentration-dependent manner. However, the platelets incubated with PKC inhibitor did not results in ΔΨm depolarization and PS exposure. It is concluded that the PKC activation induces platelet apoptosis through influencing the mitochondrial functions and activating caspase 3. The finds suggest a novel mechanism for PKC in regulating platelet numbers and functions, which has important pathophysiological implications for thrombosis and hemostasis.

  12. Inherited platelet disorders and oral health.

    Science.gov (United States)

    Valera, Marie-Cécile; Kemoun, Philippe; Cousty, Sarah; Sie, Pierre; Payrastre, Bernard

    2013-02-01

    Platelets play a key role in thrombosis and hemostasis. Accumulation of platelets at the site of vascular injury is the first step in the formation of hemostatic plugs, which play a pivotal role in preventing blood loss after injury. Platelet adhesion at sites of injury results in spreading, secretion, recruitment of additional platelets, and formation of platelet aggregates. Inherited platelet disorders are rare causes of bleeding syndromes, ranging from mild bruising to severe hemorrhage. The defects can reflect deficiency or dysfunction of platelet surface glycoproteins, granule contents, cytoskeletal proteins, platelet pro-coagulant function, and signaling pathways. For instance, Bernard-Soulier syndrome and Glanzmann thrombasthenia are attributed to deficiencies of glycoprotein Ib/IX/V and GPIIb/IIIa, respectively, and are rare but severe platelet disorders. Inherited defects that impair platelet secretion and/or signal transduction are among the most common forms of mild platelet disorders and include gray platelet syndrome, Hermansky-Pudlak syndrome, and Chediak-Higashi syndrome. When necessary, desmopressin, antifibrinolytic agents, and transfusion of platelets remain the most common treatment of inherited platelet disorders. Alternative therapies such as recombinant activated factor VII are also available for a limited number of situations. In this review, we will discuss the management of patients with inherited platelet disorders in various clinical situations related to dental cares, including surgical intervention. © 2012 John Wiley & Sons A/S.

  13. Platelet full length TFPI-α in healthy volunteers is not affected by sex or hormonal use

    Science.gov (United States)

    Winckers, Kristien; Thomassen, Stella; ten Cate, Hugo; Hackeng, Tilman M.

    2017-01-01

    Background Only 10% of plasma TFPIα (TFPI) exists in the full length form, the rest circulates as a C-terminally truncated form. However, blood platelets exclusively contain full length TFPI, which is released at the site of injury upon platelet activation, and which could play an important local regulatory role in thrombin generation and prevention of thrombosis. Methods The anticoagulant activities of full length and truncated TFPI were investigated using thrombin generation assays. Blood samples were obtained from 30 healthy volunteers (10 male subjects, 10 female subjects, and 10 females using oral contraceptives). Platelet TFPI was released in platelet rich plasma and in platelet isolates using convulxin or thrombin, and measured by free TFPI ELISA and thrombin generation assays. Results Full length TFPI and platelet TFPI were much more potent inhibitors of thrombin generation than truncated TFPI, which was virtually inactive. Although mean plasma TFPI antigen levels decreased from men (0.30 nM) to women (0.20 nM) to women using oral contraceptives (0.11 nM), no relevant differences were found in platelet TFPI among those subgroups. Conclusions Platelets release similar amounts of TFPI regardless of plasma TFPI concentrations and is unaffected by sex or oral contraceptive use. We speculate that platelet TFPI is important to prevent systemic coagulation and thrombosis and restrict thrombus formation to the site of the growing platelet plug. The stable contribution of platelet TFPI to the anticoagulant potential in plasma is likely to become particularly relevant under conditions of low plasma TFPI levels in combination of oral contraceptives use. PMID:28158181

  14. NF-κB Links TLR2 and PAR1 to Soluble Immunomodulator Factor Secretion in Human Platelets

    Science.gov (United States)

    Damien, Pauline; Cognasse, Fabrice; Payrastre, Bernard; Spinelli, Sherry L.; Blumberg, Neil; Arthaud, Charles-Antoine; Eyraud, Marie-Ange; Phipps, Richard P.; McNicol, Archibald; Pozzetto, Bruno; Garraud, Olivier; Hamzeh-Cognasse, Hind

    2017-01-01

    The primary toll-like receptor (TLR)-mediated immune cell response pathway common for all TLRs is MyD88-dependent activation of NF-κB, a seminal transcription factor for many chemokines and cytokines. Remarkably, anucleate platelets express the NF-κB machinery, whose role in platelets remains poorly understood. Here, we investigated the contribution of NF-κB in the release of cytokines and serotonin by human platelets, following selective stimulation of TLR2 and protease activated receptor 1 (PAR1), a classical and non-classical pattern-recognition receptor, respectively, able to participate to the innate immune system. We discovered that platelet PAR1 activation drives the process of NF-κB phosphorylation, in contrast to TLR2 activation, which induces a slower phosphorylation process. Conversely, platelet PAR1 and TLR2 activation induces similar ERK1/2, p38, and AKT phosphorylation. Moreover, we found that engagement of platelet TLR2 with its ligand, Pam3CSK4, significantly increases the release of sCD62P, RANTES, and sCD40L; this effect was attenuated by incubating platelets with a blocking anti-TLR2 antibody. This effect appeared selective since no modulation of serotonin secretion was observed following platelet TLR2 activation. Platelet release of sCD62P, RANTES, and sCD40L following TLR2 or PAR1 triggering was abolished in the presence of the NF-κB inhibitor Bay11-7082, while serotonin release following PAR1 activation was significantly decreased. These new findings support the concept that NF-κB is an important player in platelet immunoregulations and functions. PMID:28220122

  15. Platelet-containing tantalum powders

    Energy Technology Data Exchange (ETDEWEB)

    Schiele, E.K.

    1988-04-26

    A method of forming platelet tantalum powders is described comprising the steps of: (a) providing an ingot-derived precursor tantalum powder, and (b) ball-milling the precursor powder for a time sufficient to form a platelet powder having an average FSSS of less than about 2 micrometers, a Scott density not greater than about 30 g/in/sup 3/ and a BET surface area of at least about 0.7 in/sup 2//g.

  16. Human platelets repurposed as vehicles for in vivo imaging of myeloma xenotransplants

    Science.gov (United States)

    Dai, Lu; Gu, Ning; Chen, Bao-An; Marriott, Gerard

    2016-01-01

    Human platelets were identified in tumors by Trousseau in 1865, although their roles in tumor microenvironments have only recently attracted the attention of cancer researchers. In this study we exploit and enhance platelet interactions in tumor microenvironments by introducing tumor-targeting and imaging functions. The first step in repurposing human platelets as vehicles for tumor-targeting was to inhibit platelet-aggregation by cytoplasmic-loading of kabiramide (KabC), a potent inhibitor of actin polymerization and membrane protrusion. KabC-Platelets can accumulate high levels of other membrane-permeable cytoxins and probes, including epidoxorubicin, carboxyfluorescein di-ester and chlorin-e6. Finally, mild reaction conditions were developed to couple tumor-targeting proteins and antibodies to KabC-platelets. Fluorescence microscopy studies showed KabC-platelets, surface-coupled with transferrin and Cy5, bind specifically to RPMI8226 and K562 cells, both of which over-express the transferrin receptor. Repurposed platelets circulate for upto 9-days a feature that increases their chance of interacting with target cells. KabC-platelets, surface-coupled with transferrin and Cy7, or chlorin-e6, and injected in immuno-compromised mice were shown to accumulate specifically in sub-cutaneous and intra-cranial myeloma xenotransplants. The high-contrast, in vivo fluorescence images recorded from repurposed platelets within early-stage myeloma is a consequence in part of their large size (φ∼2μm), which allows them to transport 100 to 1000-times more targeting-protein and probe molecules respectively. Human platelets can be configured with a plurality of therapeutic and targeting antibodies to help stage tumor environments for an immunotherapy, or with combinations of therapeutic antibodies and therapeutic agents to target and treat cardiovascular and neurologic diseases. PMID:27049725

  17. Human platelets repurposed as vehicles for in vivo imaging of myeloma xenotransplants.

    Science.gov (United States)

    Dai, Lu; Gu, Ning; Chen, Bao-An; Marriott, Gerard

    2016-04-19

    Human platelets were identified in tumors by Trousseau in 1865, although their roles in tumor microenvironments have only recently attracted the attention of cancer researchers. In this study we exploit and enhance platelet interactions in tumor microenvironments by introducing tumor-targeting and imaging functions. The first step in repurposing human platelets as vehicles for tumor-targeting was to inhibit platelet-aggregation by cytoplasmic-loading of kabiramide (KabC), a potent inhibitor of actin polymerization and membrane protrusion. KabC-Platelets can accumulate high levels of other membrane-permeable cytoxins and probes, including epidoxorubicin, carboxyfluorescein di-ester and chlorin-e6. Finally, mild reaction conditions were developed to couple tumor-targeting proteins and antibodies to KabC-platelets. Fluorescence microscopy studies showed KabC-platelets, surface-coupled with transferrin and Cy5, bind specifically to RPMI8226 and K562 cells, both of which over-express the transferrin receptor. Repurposed platelets circulate for upto 9-days a feature that increases their chance of interacting with target cells. KabC-platelets, surface-coupled with transferrin and Cy7, or chlorin-e6, and injected in immuno-compromised mice were shown to accumulate specifically in sub-cutaneous and intra-cranial myeloma xenotransplants. The high-contrast, in vivo fluorescence images recorded from repurposed platelets within early-stage myeloma is a consequence in part of their large size (φ~2µm), which allows them to transport 100 to 1000-times more targeting-protein and probe molecules respectively. Human platelets can be configured with a plurality of therapeutic and targeting antibodies to help stage tumor environments for an immunotherapy, or with combinations of therapeutic antibodies and therapeutic agents to target and treat cardiovascular and neurologic diseases.

  18. [Establishment of method detecting CD36 expression on human platelet and its application].

    Science.gov (United States)

    Liu, Ying; Xu, Xian-Guo; Lan, Xiao-Fei; Ma, Kai-Rong; Chen, Shu; Hong, Xiao-Zhen; He, Ji; Zhu, Fa-Ming; Lyu, Hang-Jun

    2013-08-01

    The individual with the deficiency of CD36 antigen on platelet displayed the risk of anti-CD36 immune reaction induced by transfusion, which is one of the reasons for platelet transfusion refractoriness (PTR). This study was purposed to detect the expression level of CD36 antigen on platelet by flow cytometry among apheresis platelet donors of Hangzhou area, and the frequency of CD36 deficiency was analyzed. Platelet-rich plasma (PRP) was separated from fresh anticoagulant whole blood by centrifugation, then the platelets were washed and adjusted to 1×10(6). The platelets were incubated with FITC-labeled CD36 and PE-labeled CD41 monoclonal antibodies, then the expression level of CD36 was detected by flow cytometry. The CD36 expression on monocytes for the samples of CD36-deficiency on the platelets was further analyzed. The results showed that 7 samples with CD36 antigen deficiency were found in 192 apheresis platelet donors. The frequency of CD36 deficiency was 3.6% and all of them were typeII deficiency. The significant difference of CD36 antigen expression was observed in the platelet donors of Hangzhou population, among them 59 individuals with low expressed CD36 antigen and 126 individuals with highly expressed CD36 antigen were found according to the geometric mean fluorescence intensity. It is concluded that the CD36 antigen deficient phenotype existed in the population, these data will provide the information for research of the CD36 antigen distribution and help to solve the platelet transfusion refractoriness.

  19. Modification of Pulsed Electric Field Conditions Results in Distinct Activation Profiles of Platelet-Rich Plasma

    Science.gov (United States)

    Frelinger, Andrew L.; Gerrits, Anja J.; Garner, Allen L.; Torres, Andrew S.; Caiafa, Antonio; Morton, Christine A.; Berny-Lang, Michelle A.; Carmichael, Sabrina L.; Neculaes, V. Bogdan; Michelson, Alan D.

    2016-01-01

    Background Activated autologous platelet-rich plasma (PRP) used in therapeutic wound healing applications is poorly characterized and standardized. Using pulsed electric fields (PEF) to activate platelets may reduce variability and eliminate complications associated with the use of bovine thrombin. We previously reported that exposing PRP to sub-microsecond duration, high electric field (SMHEF) pulses generates a greater number of platelet-derived microparticles, increased expression of prothrombotic platelet surfaces, and differential release of growth factors compared to thrombin. Moreover, the platelet releasate produced by SMHEF pulses induced greater cell proliferation than plasma. Aims To determine whether sub-microsecond duration, low electric field (SMLEF) bipolar pulses results in differential activation of PRP compared to SMHEF, with respect to profiles of activation markers, growth factor release, and cell proliferation capacity. Methods PRP activation by SMLEF bipolar pulses was compared to SMHEF pulses and bovine thrombin. PRP was prepared using the Harvest SmartPreP2 System from acid citrate dextrose anticoagulated healthy donor blood. PEF activation by either SMHEF or SMLEF pulses was performed using a standard electroporation cuvette preloaded with CaCl2 and a prototype instrument designed to take into account the electrical properties of PRP. Flow cytometry was used to assess platelet surface P-selectin expression, and annexin V binding. Platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), endothelial growth factor (EGF) and platelet factor 4 (PF4), and were measured by ELISA. The ability of supernatants to stimulate proliferation of human epithelial cells in culture was also evaluated. Controls included vehicle-treated, unactivated PRP and PRP with 10 mM CaCl2 activated with 1 U/mL bovine thrombin. Results PRP activated with SMLEF bipolar pulses or thrombin had similar light scatter profiles, consistent with the

  20. In vitro function of random donor platelets stored for 7 days in composol platelet additive solution

    Directory of Open Access Journals (Sweden)

    Gupta Ashish

    2011-01-01

    Full Text Available Background and Aim: Platelets are routinely isolated from whole blood and stored in plasma for 5 days. The present study was done to assess the in vitro function of random donor platelets stored for 7 days in composol platelet additive solution at 22°C. Materials and Methods: The study sample included 30 blood donors of both sex in State Blood Bank, CSM Medical University, Lucknow. Random donor platelets were prepared by platelet rich plasma method. Whole blood (350 ml was collected in anticoagulant Citrate Phosphate Dextrose Adenine triple blood bags. Random donor platelets were stored for 7 days at 22°C in platelet incubators and agitators, with and without additive solution. Results: Platelet swirling was present in all the units at 22°C on day 7, with no evidence of bacterial contamination. Comparison of the mean values of platelet count, platelet factor 3, lactate dehydrogenase, pH, glucose and platelet aggregation showed no significant difference in additive solution, whereas platelet factor 3, glucose and platelet aggregation showed significant difference (P < 0.001 on day 7 without additive solution at 22°C. Conclusion: Our study infers that platelet viability and aggregation were best maintained within normal levels on day 7 of storage in platelet additive solution at 22°C. Thus, we may conclude that in vitro storage of random donor platelets with an extended shelf life of 7 days using platelet additive solution may be advocated to improve the inventory of platelets.

  1. Plasma rico en plaquetas Platelet -rich plasma

    Directory of Open Access Journals (Sweden)

    J. González Lagunas

    2006-04-01

    Full Text Available El Plasma Rico en Plaquetas es una suspensión concentrada de la sangre centrifugada que contiene elevadas concentraciones de trombocitos. Durante los últimos años, este producto ha aparecido de forma repetida en publicaciones científicas y en medios de comunicación generales como un producto que por sus características induce la curación y regeneración de los tejidos. La premisa de su uso es que las elevadas concentraciones de plaquetas en el PRP, liberan cantidades significativas de factores de crecimiento. En este artículo se van a recoger las evidencias científicas que se han presentado en la literatura médica con respecto al PRP y a la curación ósea, así como las diferentes aplicaciones clínicas que se han sugerido.Platelet-rich plasma is a by-product of centrifuged whole blood that contains high levels of thrombocytes. In the last decade, scientific and media interest has been generated by this product that apparently has the capacity of inducing and promoting tissue healing and regeneration. The premise of its use is that the large number of platelets in PRP release significant amounts of growth factors. In this paper, a critical review of the medical literature regarding PRP and bone healing will be presented. Also, the suggested clinical applications of the product will be addressed.

  2. Isolation and characterization of platelet-derived extracellular vesicles

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    Maria T. Aatonen

    2014-08-01

    Full Text Available Background: Platelet-derived extracellular vesicles (EVs participate, for example, in haemostasis, immunity and development. Most studies of platelet EVs have targeted microparticles, whereas exosomes and EV characterization under various conditions have been less analyzed. Studies have been hampered by the difficulty in obtaining EVs free from contaminating cells and platelet remnants. Therefore, we optimized an EV isolation protocol and compared the quantity and protein content of EVs induced by different agonists. Methods: Platelets isolated with iodixanol gradient were activated by thrombin and collagen, lipopolysaccharide (LPS or Ca2+ ionophore. Microparticles and exosomes were isolated by differential centrifugations. EVs were quantitated by nanoparticle tracking analysis (NTA and total protein. Size distributions were determined by NTA and electron microscopy. Proteomics was used to characterize the differentially induced EVs. Results: The main EV populations were 100–250 nm and over 90% were <500 nm irrespective of the activation. However, activation pathways differentially regulated the quantity and the quality of EVs, which also formed constitutively. Thrombogenic activation was the most potent physiological EV-generator. LPS was a weak inducer of EVs, which had a selective protein content from the thrombogenic EVs. Ca2+ ionophore generated a large population of protein-poor and unselectively packed EVs. By proteomic analysis, EVs were highly heterogeneous after the different activations and between the vesicle subpopulations. Conclusions: Although platelets constitutively release EVs, vesiculation can be increased, and the activation pathway determines the number and the cargo of the formed EVs. These activation-dependent variations render the use of protein content in sample normalization invalid. Since most platelet EVs are 100–250 nm, only a fraction has been analyzed by previously used methods, for example, flow cytometry. As

  3. Evidence of platelet activation in multiple sclerosis

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    Alexander J Steven

    2008-06-01

    Full Text Available Abstract Objective A fatality in one multiple sclerosis (MS patient due to acute idiopathic thrombocytopenic purpura (ITP and a near fatality in another stimulated our interest in platelet function abnormalities in MS. Previously, we presented evidence of platelet activation in a small cohort of treatment-naive MS patients. Methods In this report, 92 normal controls and 33 stable, untreated MS patients were studied. Platelet counts, measures of platelet activation [plasma platelet microparticles (PMP, P-selectin expression (CD62p, circulating platelet microaggragtes (PAg], as well as platelet-associated IgG/IgM, were carried out. In addition, plasma protein S activity was measured. Results Compared to controls, PMP were significantly elevated in MS (p Conclusion Platelets are significantly activated in MS patients. The mechanisms underlying this activation and its significance to MS are unknown. Additional study of platelet activation and function in MS patients is warranted.

  4. A comparison of a solid phase IRC assay and the PSIFT for detection of antibodies to platelets.

    Science.gov (United States)

    Häcker-Shahin, B; Giannitsis, D J

    1992-01-01

    A rapid solid phase indicator red cells assay (IRCA) for detection of platelet antibodies was developed and its sensitivity compared with PSIFT. Platelets were attached to the surface of polystyrene microtitre plate wells by means of a sodium carbonate buffer and centrifugation. Uncovered areas were blocked by a gelatin blocking buffer. After serum incubation bound platelet-specific antibodies were made visible by anti-IgG-coated indicator red cells and a brief centrifugation. A positive result, meaning the presence of an anti-platelet antibody was indicated by red cell adherence over the reaction surface. In the absence of serum antibodies to platelets the indicator red cells formed a pellet. The IRCA showed a high sensitivity; the anti-platelet antibody Thrombocyte was detectable until a dilution of 1:1,600 whereas the same antibody in the PSIFT could only be detected until a dilution of 1:400.

  5. Regulation of corticotropin releasing hormone receptor type 1 messenger RNA level in Y-79 retinoblastoma cells: potential implications for human stress response and immune/inflammatory reaction

    OpenAIRE

    Vamvakopoulos, N C; Sioutopoulou, T. O.; Mamuris, Z.; Marcoulatos, P.; Avgerinos, P. C.

    1996-01-01

    We report the regulation of type 1 receptor mRNA in Y-79 human retinoblastoma cells, grown in the absence or presence of pharmacological levels of phorbol esters, forskolin, glucocorticoids and their combinations. To control for inducibility and for assessing the sensitivity of the Y-79 system to glucocorticoids, corticotropin releasing hormone mRNA levels were measured in parallel. All treatments stimulated corticotropin releasing hormone receptor type 1 gene expression relative to baseline....

  6. Model studies on the release of aroma compounds from structured and nonstructured oil systems using proton-transfer reaction mass spectrometry.

    Science.gov (United States)

    Landy, Pascale; Pollien, Philippe; Rytz, Andreas; Leser, Martin E; Sagalowicz, Laurent; Blank, Imre; Spadone, Jean-Claude

    2007-03-07

    Relative retention, volatility, and temporal release of volatile compounds taken from aldehyde, ester, and alcohol chemical classes were studied at 70 degrees C in model systems using equilibrium static headspace analysis and real time dynamic headspace analysis. These systems were medium-chain triglycerides (MCT), sunflower oil, and two structured systems, i.e., water-in-oil emulsion and L2 phase (water-in-oil microemulsion). Hydrophilic domains of the emulsion type media retained specifically the hydrophilic compounds and alcohols. Four kinetic parameters characterizing the concentration- and time-dependent releases were extracted from the aroma release curves. Most of the kinetic parameter values were higher in structured systems than in oils particularly when using MCT. The oil nature was found to better control the dynamic release profiles than the system structures. The release parameters were well-related (i) to the volatile hydrophobicity as a function of the oil used and (ii) to the retention data in the specific case of the L2 phase due to a specific release behavior of alcohols.

  7. The Inflammatory Role of Platelets: Translational Insights from Experimental Studies of Autoimmune Disorders

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    Susann Pankratz

    2016-10-01

    Full Text Available Beyond their indispensable role in hemostasis, platelets have shown to affect the development of inflammatory disorders, as they have been epidemiologically and mechanistically linked to diseases featuring an inflammatory reaction in inflammatory diseases like multiple sclerosis, rheumatoid arthritis and inflammatory bowel disorders. The identification of novel molecular mechanisms linking inflammation and to platelets has highlighted them as new targets for therapeutic interventions. In particular, genetic and pharmacological studies have identified an important role for platelets in neuroinflammation. This review summarizes the main molecular links between platelets and inflammation, focusing on immune regulatory factors, receptors, cellular targets and signaling pathways by which they can amplify inflammatory reactions and that make them potential therapeutic targets.

  8. Network reconstruction of platelet metabolism identifies metabolic signature for aspirin resistance

    Science.gov (United States)

    Thomas, Alex; Rahmanian, Sorena; Bordbar, Aarash; Palsson, Bernhard Ø.; Jamshidi, Neema

    2014-01-01

    Recently there has not been a systematic, objective assessment of the metabolic capabilities of the human platelet. A manually curated, functionally tested, and validated biochemical reaction network of platelet metabolism, iAT-PLT-636, was reconstructed using 33 proteomic datasets and 354 literature references. The network contains enzymes mapping to 403 diseases and 231 FDA approved drugs, alluding to an expansive scope of biochemical transformations that may affect or be affected by disease processes in multiple organ systems. The effect of aspirin (ASA) resistance on platelet metabolism was evaluated using constraint-based modeling, which revealed a redirection of glycolytic, fatty acid, and nucleotide metabolism reaction fluxes in order to accommodate eicosanoid synthesis and reactive oxygen species stress. These results were confirmed with independent proteomic data. The construction and availability of iAT-PLT-636 should stimulate further data-driven, systems analysis of platelet metabolism towards the understanding of pathophysiological conditions including, but not strictly limited to, coagulopathies.

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

    Science.gov (United States)

    Yazdani, Alireza; Li, Zhen; Karniadakis, George

    2015-11-01

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

  10. Synthesis and Vasorelaxant and Platelet Antiaggregatory Activities of a New Series of 6-Halo-3-phenylcoumarins

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    Dolores Viña

    2010-01-01

    Full Text Available A series of 6-halo-3-hydroxyphenylcoumarins (resveratrol-coumarins hybrid derivatives was synthesized in good yields by a Perkin reaction followed by hydrolysis. The new compounds were evaluated for their vasorelaxant activity in intact rat aorta rings pre-contracted with phenylephrine (PE, as well as for their inhibitory effects on platelet aggregation induced by thrombin in washed human platelets. These compounds concentration-dependently relaxed vascular smooth muscle and some of them showed a platelet antiaggregatory activity that was up to thirty times higher than that shown by trans-resveratrol and some other previously synthesized derivatives.

  11. Roles of Mac-1 and glycoprotein IIb/IIIa integrins in leukocyte-platelet aggregate formation: stabilization by Mac-1 and inhibition by GpIIb/IIIa blockers.

    Science.gov (United States)

    Patko, Zsofia; Csaszar, Albert; Acsady, Gyorgy; Peter, Karlheinz; Schwarz, Meike

    2012-01-01

    Circulating platelet-leukocyte hetero-aggregates play an important role in acute cardiovascular events and hypersensitivity reactions. The association involves the receptor families of selectins and integrin. The objective of this study was to investigate the role of CD11b/CD18 integrin (Mac-1) in hetero-aggregate formation and search for a counter-receptor on platelets ready to interact with Mac-1. As a model of leukocytes, Mac-1 presenting Chinese hamster ovary (CHO) cells were used to evaluate the role of Mac-1 in hetero-aggregate formation. The amount of CHO cell-bound active and inactive platelets was measured by flow cytometry, while the counter-receptors on platelets were identified via using blocking antibodies. We observed significant platelet adhesion on Mac-1-bearing cells when platelet-rich plasma or activated platelets were present. Inactive platelets did not adhere to Mac-1-bearing cells. Addition of fibrinogen, a ligand of Mac-1 significantly increased platelet binding. CD40L was demonstrated to act similarly on Mac-1. Inhibition of platelet GpIIb/IIIa completely abolished CHO cell-platelet aggregation. In our study, we have shown for the first time that Mac-1 mediates the formation of hetero-aggregates without selectin tethering when Mac-1 ligands such as fibrinogen or CD40L are present and blockers of platelet GpIIb/IIIa are able to diminish this interaction.

  12. The nitric oxide donor pentaerythritol tetranitrate reduces platelet activation in congestive heart failure.

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    Ulrike Flierl

    Full Text Available Platelet activation associated with endothelial dysfunction and impaired endogenous platelet inhibition is part of the cardiovascular phenotype of congestive heart failure (CHF and contributes to the increased risk for thromboembolic complications. Pentaerythritol tetranitrate (PETN has been shown to release nitric oxide without development of nitrate tolerance. We investigated the effect of chronic PETN treatment on platelet activation and aggregation in an experimental CHF model.Chronic ischemic heart failure was induced in male Wistar rats by coronary artery ligation. Starting 7 days thereafter, rats were randomised to placebo or PETN (80 mg/kg twice daily. After 9 weeks, activation of circulating platelets was determined measuring platelet bound fibrinogen, which requires activated glycoprotein IIb/IIIa on the platelet surface. Binding was quantified by flow-cytometry using a FITC-labelled anti-fibrinogen antibody. Platelet-bound fibrinogen was significantly increased in CHF-Placebo (mean fluorescence intensity: Sham 88±4, CHF-Placebo 104±6, p<0.05 and reduced following treatment with PETN (89±7, p<0.05 vs. CHF-Placebo. Maximal and final ADP-induced aggregation was significantly enhanced in CHF-Placebo vs. Sham-operated animals and normalized / decreased following chronic PETN treatment. Moreover, platelet adhesion was significantly reduced (number of adherent platelets: control: 85.6±5.5, PETN: 40±3.3; p<0.001 and VASP phosphorylation significantly enhanced following in vitro PETN treatment.Chronic NO supplementation using PETN reduces platelet activation in CHF rats. Thus, PETN may constitute a useful approach to prevent thromboembolic complications in CHF.

  13. Impact of reticulated platelets on antiplatelet response to thienopyridines is independent of platelet turnover.

    Science.gov (United States)

    Stratz, Christian; Nührenberg, Thomas; Amann, Michael; Cederqvist, Marco; Kleiner, Pascal; Valina, Christian M; Trenk, Dietmar; Neumann, Franz-Josef; Hochholzer, Willibald

    2016-10-28

    Reticulated platelets are associated with impaired antiplatelet response to thienopyridines. It is uncertain whether this interaction is caused by a decreased drug exposure due to high platelet turnover reflected by elevated levels of reticulated platelets or by intrinsic properties of reticulated platelets. This study sought to investigate if the impact of reticulated platelets on early antiplatelet response to thienopyridines is mainly caused by platelet turnover as previously suggested. Elective patients undergoing coronary intervention were randomised to loading with clopidogrel 600 mg or prasugrel 60 mg (n=200). Adenosine diphosphate (ADP)-induced platelet reactivity was determined by impedance aggregometry before, at 30, 60, 90, and 120 minutes and at day 1 after loading. Immature platelet count was assessed as marker of reticulated platelets by flow cytometry. Platelet reactivity increased with rising levels of immature platelet count in both groups. This effect was more distinctive in patients on clopidogrel as compared to patients on prasugrel. Overall, immature platelet count correlated well with on-treatment platelet reactivity at all time-points (p < 0.001). These correlations did not change over time in the entire cohort as well as in patients treated with clopidogrel or prasugrel indicating an effect independent of platelet turnover (comparison of correlations 120 minutes/day 1: p = 0.64). In conclusion, the association of immature platelet count with impaired antiplatelet response to thienopyridines is similar early and late after loading. This finding suggests as main underlying mechanism another effect of reticulated platelets on thienopyridines than platelet turnover.

  14. Platelets--an important element of the immune system.

    Science.gov (United States)

    Trzeciak-Ryczek, A; Tokarz-Deptuła, B; Deptuła, W

    2013-01-01

    Platelets are anucleate cells derived from the megakaryocyte series, and have long been considered only as cells responsible for coagulation and the fibrinolysis process. However, recently more data shows that they are also effector cells in the inflammatory response and important elements of the immunological response. Platelets store and release many biologically active substances, including growth factors, cytokines and chemokines (tab. 1), which actively affect i.a. elements of the immune system, and thus become regulators of immunity and mediators of inflammatory response. Their impact on the immune system cells is also associated with the induction of leucocytes and progenitor cells to the site of pathogen permeation or vascular injury inflow, as well as endothelial cells. Interacting with neutrophils, monocytes and lymphocytes, they not only activate them, but also form platelet-leukocyte aggregates that immobilise pathogens and prevent their spreading. Furthermore, platelets are capable of absorbing pathogens, affecting anti-infection immunity of the system. It is also assumed that the presence of receptors on their surface, such as Toll-like receptors (TLRs), affects their initiation and activity of the immunological response.

  15. Surface morphology of platelet adhesion influenced by activators, inhibitors and shear stress

    Science.gov (United States)

    Watson, Melanie Groan

    Platelet activation involves multiple events, one of which is the generation and release of nitric oxide (NO), a platelet aggregation inhibitor. Platelets simultaneously send and receive various agents that promote a positive and negative feedback control system during hemostasis. Although the purpose of platelet-derived NO is not fully understood, NO is known to inhibit platelet recruitment. NO's relatively large diffusion coefficient allows it to diffuse more rapidly than platelet agonists. It may thus be able to inhibit recruitment of platelets near the periphery of a growing thrombus before agonists have substantially accumulated in those regions. Results from two studies in our laboratory differed in the extent to which platelet-derived NO decreased platelet adhesion. Frilot studied the effect of L-arginine (L-A) and NG-Methyl-L-arginine acetate salt (L-NMMA) on platelet adhesion to collagen under static conditions in a Petri dish. Eshaq examined the percent coverage on collagen-coated and fibrinogen-coated microchannels under shear conditions with different levels of L-A and Adenosine Diphosphate (ADP). Frilot's results showed no effect of either L-A or L-NMMA on surface coverage, thrombus size or serotonin release, while Eshaq's results showed a decrease in surface coverage with increased levels of L-A. A possible explanation for these contrasting results is that platelet-derived NO may be more important under flow conditions than under static conditions. For this project, the effects of L-A. ADP and L-NMMA on platelet adhesion were studied at varying shear stresses on protein-coated glass slides. The surface exposed to platelet-rich-plasma in combination with each chemical solution was observed under AFM, FE-SEM and fluorescence microscopy. Quantitative and qualitative comparisons of images obtained with these techniques confirmed the presence of platelets on the protein coatings. AFM images of fibrinogen and collagen-coated slides presented characteristic

  16. Platelet satellitism in infectious disease?

    Science.gov (United States)

    Laskaj, Renata; Sikiric, Dubravka; Skerk, Visnja

    2015-01-01

    Background Platelet satellitism is a phenomenon of unknown etiology of aggregating platelets around polymorphonuclear neutrophils and other blood cells which causes pseudothrombocytopenia, visible by microscopic examination of blood smears. It has been observed so far in about a hundred cases in the world. Case subject and methods Our case involves a 73-year-old female patient with a urinary infection. Biochemical serum analysis (CRP, glucose, AST, ALT, ALP, GGT, bilirubin, sodium, potassium, chloride, urea, creatinine) and blood cell count were performed with standard methods on autoanalyzers. Serum protein fractions were examined by electrophoresis and urinalysis with standard methods on autoanalyzer together with microscopic examination of urine sediment. Erythrocyte sedimentation rate, blood culture and urine culture tests were performed with standard methods. Results Due to typical pathological values for bacterial urinary infection, the patient was admitted to the hospital. Blood smear examination revealed phenomenon, which has persisted for three weeks after the disease has been cured. Blood smears with EDTA as an anticoagulant had platelet satellitism whereas the phenomenon was not observed in tubes with different anticoagulants (Na, Li-heparin) and capillary blood. Discussion We hypothesize that satellitism was induced by some immunological mechanism through formation of antibodies which have mediated platelets binding to neutrophil membranes and vice versa. Unfortunately we were unable to determine the putative trigger for this phenomenon. To our knowledge this is the second case of platelet satellitism ever described in Croatia. PMID:26110042

  17. Influenza virus H1N1 activates platelets through FcγRIIA signaling and thrombin generation.

    Science.gov (United States)

    Boilard, Eric; Paré, Guillaume; Rousseau, Matthieu; Cloutier, Nathalie; Dubuc, Isabelle; Lévesque, Tania; Borgeat, Pierre; Flamand, Louis

    2014-05-01

    Platelets play crucial functions in hemostasis and the prevention of bleeding. During H1N1 influenza A virus infection, platelets display activation markers. The platelet activation triggers during H1N1 infection remain elusive. We observed that H1N1 induces surface receptor activation, lipid mediator synthesis, and release of microparticles from platelets. These activation processes require the presence of serum/plasma, pointing to the contribution of soluble factor(s). Considering that immune complexes in the H1N1 pandemic were reported to play a pathogenic role, we assessed their contribution in H1N1-induced platelet activation. In influenza-immunized subjects, we observed that the virus scaffolds with immunoglobulin G (IgG) to form immune complexes that promote platelet activation. Mechanistically, this activation occurs through stimulation of low-affinity type 2 receptor for Fc portion of IgG (FcγRIIA), a receptor for immune complexes, independently of thrombin. Using a combination of in vitro and in vivo approaches, we found that the antibodies from H3N2-immunized mice activate transgenic mouse platelets that express FcγRIIA when put in the presence of H1N1, suggesting that cross-reacting influenza antibodies suffice. Alternatively, H1N1 can activate platelets via thrombin formation, independently of complement and FcγRIIA. These observations identify both the adaptive immune response and the innate response against pathogens as 2 intertwined processes that activate platelets during influenza infections.

  18. Involvement of platelet-tumor cell interaction in immune evasion. Potential role of podocalyxin-like protein 1

    Directory of Open Access Journals (Sweden)

    Laura eAmo

    2014-09-01

    Full Text Available Besides their essential role in hemostasis and thrombosis, platelets are involved in the onset of cancer metastasis by interacting with tumor cells. Platelets release secretory factors that promote tumor growth, angiogenesis, and metastasis. Furthermore, the formation of platelet-tumor cell aggregates in the bloodstream provides cancer cells with an immune escape mechanism by protecting circulating malignant cells from immune-mediated lysis by natural killer (NK cells. Platelet-tumor cell interaction is accomplished by specific adhesion molecules, including integrins, selectins, and their ligands. Podocalyxin-like protein 1 (PCLP1 is a selectin ligand protein which overexpression has been associated with several aggressive cancers. PCLP1 expression enhances cell adherence to platelets in an integrin-dependent process and through the interaction with P-selectin expressed on activated platelets. However, the involvement of PCLP1-induced tumor-platelet interaction in tumor immune evasion still remains unexplored. The identification of selectin ligands involved in the interaction of platelets with tumor cells may provide help for the development of effective therapies to restrain cancer cell dissemination. This article summarizes the current knowledge on molecules that participate in platelet-tumor cell interaction as well as discusses the potential role of PCLP1 as a molecule implicated in tumor immune evasion.

  19. Evaluation of platelet aggregation in platelet concentrates: storage implications

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    Neiva Teresinha J.C.

    2003-01-01

    Full Text Available The use of hemo-derivatives is nowadays a fundamentally important therapeutic modality in the exercise of medicine. Among the various hemo-components employed, we have the platelet concentrate (PC, indicated in cases of hemorrhagic disturbances. We previously showed that platelet function in blood donors is reduced in their screening phase and after the separation process of PCs. Currently, we are providing evidence for the existence of biochemical and functional changes in PC preparations stored for three days at temperatures of 20 ± 2 ºC. Platelet concentrates from 40 healthy donors, collected in CPD anticoagulant and PL-146 polyvinylchloride containers, were examined in order to determine the pH value, pCO2 ,pO2 and lactate concentrations. In addition, the aggregation of platelets with thrombin and collagen were examined to evaluate platelet function. A pH increase from 7.07 ± 0.04 to 7.36 ± 0.07 (p < 0.01 was observed. The pCO2 concentration decreased progressively from 69.2 ± 7.7 mmHg to 28.8 ± 6.2 mmHg (p < 0.001 during the storage period. In contrast, pO2 value increase from 103.4 ± 30.6 to 152.3 ± 24.6 mmHg (p < 0.001 was evidenced during the 48 hours of storage. The lactate concentration increased from 17.97 ± 5.2 to 57.21 ± 5.7 mg/dl (p < 0.001. Platelet aggregation using 0.25 U/ml-thrombin and 2.0 µg/ml-collagen showed significant hypofunction from 61.8 ± 2.7% to 24.8 ± 9.8% and 62.7±5.0 to 33.4± 6.2 (p < 0.001, respectively. We concluded that the evaluated biochemical parameters and the platelet function changed significantly when the platelets were kept under routine storage conditions.

  20. Aspirin, platelets, and cancer: The point of view of the internist.

    Science.gov (United States)

    Santilli, F; Boccatonda, A; Davì, G

    2016-10-01

    Growing evidence suggests the beneficial effect of aspirin against some types of cancer, particularly of the gastrointestinal tract, and it has been provided for an effect both in cancer prevention as well as in survival improvement of cancer patients. Aspirin benefits increase with duration of treatment, especially after 10years of treatment. The inhibition of platelet activation at sites of gastrointestinal mucosal lesions could be the primary mechanism of action of low-dose aspirin. Indeed, the formation of tumor cell-induced platelet aggregates may favor immune evasion, by releasing angiogenic and growth factors, and also by promoting cancer cell dissemination. Moreover, platelets may contribute to aberrant COX-2 expression in colon carcinoma cells, thereby contributing to downregulation of oncosuppressor genes and upregulation of oncogenes, such as cyclin B1. Platelet adhesion to cancer cells leads also to an increased expression of genes involved in the EMT, such as the EMT-inducing transcription factors ZEB1 and TWIST1 and the mesenchymal marker vimentin. The aspirin-mediated inactivation of platelets may restore antitumor reactivity by blocking the release of paracrine lipid and protein mediators that induce COX-2 expression in adjacent nucleated cells at sites of mucosal injury. Thus, recent findings suggest interesting perspectives on "old" aspirin and NSAID treatment and/or "new" specific drugs to target the "evil" interactions between platelets and cancer for chemoprevention. Copyright © 2016 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.

  1. β1 integrin-mediated signals are required for platelet granule secretion and hemostasis in mouse.

    Science.gov (United States)

    Petzold, Tobias; Ruppert, Raphael; Pandey, Dharmendra; Barocke, Verena; Meyer, Hannelore; Lorenz, Michael; Zhang, Lin; Siess, Wolfgang; Massberg, Steffen; Moser, Markus

    2013-10-10

    Integrins are critical for platelet adhesion and aggregation during arterial thrombosis and hemostasis. Although the platelet-specific αIIbβ3 integrin is known to be crucial for these processes, the in vivo role of β1 integrins is a matter of debate. Here we demonstrate that mice expressing reduced levels of β1 integrins or an activation-deficient β1 integrin show strongly reduced platelet adhesion to collagen in vitro and in a carotis ligation model in vivo. Interestingly, hypomorphic mice expressing only 3% of β1 integrins on platelets show normal bleeding times despite reduced platelet adhesion. The residual 3% of β1 integrins are able to trigger intracellular signals driving Rac-1-dependent granule release required for platelet aggregation and hemostasis. Our findings support a model, in which platelet β1 integrins serve as an important signaling receptor rather than an adhesion receptor in vivo and therefore promote β1 integrins as a promising and so far clinically unemployed antithrombotic target.

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

    Science.gov (United States)

    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

  3. An overview of platelet indices and methods for evaluating platelet function in thrombocytopenic patients

    DEFF Research Database (Denmark)

    Vinholt, Pernille Just; Hvas, Anne-Mette; Nybo, Mads

    2014-01-01

    in thrombocytopenia. Flow cytometry, platelet aggregometry and platelet secretion tests are used to diagnose specific platelet function defects. The flow cytometric activation marker P-selectin and surface coverage by the Cone and Plate[let] analyser™ predict bleeding in selected thrombocytopenic populations...

  4. Platelet antigens and antibodies. Literature review

    Directory of Open Access Journals (Sweden)

    N. V. Mineeva

    2013-01-01

    Full Text Available Platelet antigens structure, role of platelet antibodies in the pathogenesis of various clinical conditions, characteristic of modern antibodies detection methods are presented in this article.

  5. Platelet antigens and antibodies. Literature review

    Directory of Open Access Journals (Sweden)

    N. V. Mineeva

    2014-07-01

    Full Text Available Platelet antigens structure, role of platelet antibodies in the pathogenesis of various clinical conditions, characteristic of modern antibodies detection methods are presented in this article.

  6. Effect of photodynamic therapy on mouse platelets

    Science.gov (United States)

    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.

  7. Platelet Disorders: MedlinePlus Health Topic

    Science.gov (United States)

    ... Article: Erythropoietin and thrombopoietin mimetics: Natural alternatives to erythrocyte and platelet... Article: Detection of CALR Mutation in Clonal and Nonclonal Hematologic Diseases... Platelet Disorders -- see more articles Thrombocytopenias -- see more ...

  8. Glycoprotein Ibα receptor instability is associated with loss of quality in platelets produced in culture.

    Science.gov (United States)

    Robert, Amélie; Boyer, Lucie; Pineault, Nicolas

    2011-03-01

    The development of culture processes for hematopoietic progenitors could lead to the development of a complementary source of platelets for therapeutic purposes. However, functional characterization of culture-derived platelets remains limited, which raises some uncertainties about the quality of platelets produced in vitro. The aim of this study was to define the proportion of functional platelets produced in cord blood CD34+ cell cultures. Toward this, the morphological and functional properties of culture-derived platelet-like particles (PLPs) were critically compared to that of blood platelets. Flow cytometry combined with transmission electron microscopy analyses revealed that PLPs formed a more heterogeneous population of platelets at a different stage of maturation than blood platelets. The majority of PLPs harbored the fibrinogen receptor αIIbβ3, but a significant proportion failed to maintain glycoprotein (GP)Ibα surface expression, a component of the vWF receptor essential for platelet functions. Importantly, GPIbα extracellular expression correlated closely with platelet function, as the GPIIb+ GPIbα+ PLP subfraction responded normally to agonist stimulation as evidenced by α-granule release, adhesion, spreading, and aggregation. In contrast, the GPIIb+ GPIbα⁻ subfraction was unresponsive in most functional assays and appeared to be metabolically inactive. The present study confirms that functional platelets can be generated in cord blood CD34+ cell cultures, though these are highly susceptible to ectodomain shedding of receptors associated with loss of function. Optimization of culture conditions to prevent these deleterious effects and to homogenize PLPs is necessary to improve the quality and yields of culture-derived platelets before they can be recognized as a suitable complementary source for therapeutic purposes.

  9. Tissue reactions to bacteria-inoculated rat lead samples .2. Effect of local gentamicin release through surface-modified polyurethane tubing

    NARCIS (Netherlands)

    vanWachem, PB; vanLuyn, MJA; deWit, AW; Raatjes, D; Hendriks, M; Verhoeven, MLPM; Cahalan, PT

    1997-01-01

    A surface modification technique was developed to achieve controlled release of gentamicin from implanted polyurethane (PU) rat lead samples. PU tubing first was provided with an acrylic acid/acrylamide copolymer surface graft and then loaded with gentamicin. This surface modification technique resu

  10. No positive effect of autologous platelet gel after total knee arthroplasty A double-blind randomized controlled trial: 102 patients with a 3-month follow-up

    NARCIS (Netherlands)

    Peerbooms, J.C.; de Wolf, G.S.; Colaris, J.W.; Bruijn, D.J.; Verhaar, J.A.N.

    2009-01-01

    Background and purpose Activated platelets release a cocktail of growth factors, some of which are thought to stimulate repair. We investigated whether the use of autologous platelet gel (PG) in total knee arthroplasty (TKA) would improve wound healing and knee function, and reduce blood loss and th

  11. No positive effect of autologous platelet gel after total knee arthroplasty: A double-blind randomized controlled trial: 102 patients with a 3-month follow-up

    NARCIS (Netherlands)

    J.C. Peerbooms (Joost); G.S. de Wolf (Gideon); J.W. Colaris (Joost); D.J. Bruijn (Danil); J.A.N. Verhaar (Jan)

    2009-01-01

    textabstractBackground and purpose Activated platelets release a cocktail of growth factors, some of which are thought to stimulate repair. We investigated whether the use of autologous platelet gel (PG) in total knee arthroplasty (TKA) would improve wound healing and knee function, and reduce blood

  12. Platelet activation attracts a subpopulation of effector monocytes to sites of Leishmania major infection.

    Science.gov (United States)

    Goncalves, Ricardo; Zhang, Xia; Cohen, Heather; Debrabant, Alain; Mosser, David M

    2011-06-01

    Leishmania species trigger a brisk inflammatory response and efficiently induce cell-mediated immunity. We examined the mechanisms whereby leukocytes were recruited into lesions after Leishmania major infection of mice. We found that a subpopulation of effector monocytes expressing the granulocyte marker GR1 (Ly6C) is rapidly recruited into lesions, and these monocytes efficiently kill L. major parasites. The recruitment of this subpopulation of monocytes depends on the chemokine receptor CCR2 and the activation of platelets. Activated platelets secrete platelet-derived growth factor, which induces the rapid release of CCL2 from leukocytes and mesenchymal cells. This work points to a new role for platelets in host defense involving the selective recruitment of a subpopulation of effector monocytes from the blood to efficiently kill this intracellular parasite.

  13. [In vitro study of platelet preservation during 5 days in reduced-thickness bags].

    Science.gov (United States)

    Domenech, J; Babault, C; Desbois, I; Degenne, M; Binet, C; Garnier, C; Chassaigne, M

    1989-02-01

    An in vitro study of platelet concentrates storage for 5 days was performed in PVC bags. Modification of the original three-day containers were introduced by thickness reduction. The results at fifth day were comparable to those at third day in standard plastic bags. During storage, variations of platelet counts were very slight with a low LDH release. PH was stable with a good maintenance of phase microscope platelet morphology. PCO2 and PO2 measurements showed a satisfactory gas permeability which could explain a limited lactate production. If in vivo studies of transfusion recovery confirm these data, platelet concentrates storage could be extended up to 5 days by such modifications of standard three-day PVC bags.

  14. Effect of platelet age on adhesiveness to collagen and platelet surface charge

    Energy Technology Data Exchange (ETDEWEB)

    Castellan, R.M.; Steiner, M.

    1976-11-30

    Adhesion to collagen was investigated as a function of platelet age in rat platelets. Platelet adherence was measured using EDTA-containing platelet- rich plasma which was added to preparations of collagen fibers clamped between magnetic stirrers by recording changes in light transmission. The plot of light transmission versus logarithm of time was linear and allowed calculation of a slope factor which related to the rate of adherence. Neither the amount of collagen nor the platelet count were limiting in the test. Young platelet populations (less than or equal to 1 day old) were obtained during the recovery phase from immune induced thrombocytopenia. Old platelet populations were prepared by blocking thrombopoiesis with cyclophosphamide. Young platelets did not differ significantly from randomly aged platelets in this function. The electrophoretic mobility of platelets was not affected by their age.

  15. Sonogashira and "Click" reactions for the N-terminal and side-chain functionalization of peptides with [Mn(CO)3(tpm)]+-based CO releasing molecules (tpm = tris(pyrazolyl)methane).

    Science.gov (United States)

    Pfeiffer, Hendrik; Rojas, Alfonso; Niesel, Johanna; Schatzschneider, Ulrich

    2009-06-14

    A recently identified photoactivatable CO releasing molecule (CORM) based on [Mn(CO)(3)(tpm)](+) was conjugated to functionalized amino acids and model peptides using the Pd-catalyzed Sonogashira cross-coupling and the alkyne-azide 1,3-dipolar cycloaddition ("Click reaction"). Both were found to be fully compatible with all functional groups present. The CORM-peptide conjugates were isolated in reasonable yield and high purity, as indicated by IR spectroscopy, ESI mass spectrometry and RP-HPLC. The myoglobin assay was used to demonstrate that they have CO release properties identical those of the parent compound. This work thus opens the way for a targeted delivery of CORMs to cellular systems.

  16. Dengue platelets meet Sir Arthur Conan Doyle.

    Science.gov (United States)

    Bray, Paul F

    2013-11-14

    In this issue of Blood, Hottz et al provide compelling evidence that dengue virus (DV) induces (1) platelet synthesis of interleukin-1b (IL-1b); (2) platelet-derived IL-1b–containing microvesicles (MVs) that increase vascular permeability; and (3) DV-triggered inflammasome activation in platelets.

  17. Platelet regulating properties of insulin revisited

    NARCIS (Netherlands)

    Andrade Ferreira, I. (Irlando)

    2005-01-01

    Disturbances in platelet responsiveness in diabetes mellitus (DM) lead to platelet-dependent complications in the vasculature. Our studies showed that insulin inhibits platelet activation by inhibiting ADP- and thrombin-induced Ca2+ levels. Ca2+ is under control of cAMP that is a potent endogenous p

  18. Image analysis of blood platelets adhesion.

    Science.gov (United States)

    Krízová, P; Rysavá, J; Vanícková, M; Cieslar, P; Dyr, J E

    2003-01-01

    Adhesion of blood platelets is one of the major events in haemostatic and thrombotic processes. We studied adhesion of blood platelets on fibrinogen and fibrin dimer sorbed on solid support material (glass, polystyrene). Adhesion was carried on under static and dynamic conditions and measured as percentage of the surface covered with platelets. Within a range of platelet counts in normal and in thrombocytopenic blood we observed a very significant decrease in platelet adhesion on fibrin dimer with bounded active thrombin with decreasing platelet count. Our results show the imperative use of platelet poor blood preparations as control samples in experiments with thrombocytopenic blood. Experiments carried on adhesive surfaces sorbed on polystyrene showed lower relative inaccuracy than on glass. Markedly different behaviour of platelets adhered on the same adhesive surface, which differed only in support material (glass or polystyrene) suggest that adhesion and mainly spreading of platelets depends on physical quality of the surface. While on polystyrene there were no significant differences between fibrin dimer and fibrinogen, adhesion measured on glass support material markedly differed between fibrin dimer and fibrinogen. We compared two methods of thresholding in image analysis of adhered platelets. Results obtained by image analysis of spreaded platelets showed higher relative inaccuracy than results obtained by image analysis of platelets centres and aggregates.

  19. The effects of residual platelets in plasma on plasminogen activator inhibitor-1 and plasminogen activator inhibitor-1-related assays

    Science.gov (United States)

    Barnard, Sunelle A.; Loots, Du Toit; Rijken, Dingeman C.

    2017-01-01

    Due to controversial evidence in the literature pertaining to the activity of plasminogen activator inhibitor-1 in platelets, we examined the effects of residual platelets present in plasma (a potential pre-analytical variable) on various plasminogen activator inhibitor-1 and plasminogen activator inhibitor-1-related assays. Blood samples were collected from 151 individuals and centrifuged at 352 and 1500 g to obtain plasma with varying numbers of platelet. In a follow-up study, blood samples were collected from an additional 23 individuals, from whom platelet-poor (2000 g), platelet-containing (352 g) and platelet-rich plasma (200 g) were prepared and analysed as fresh-frozen and after five defrost-refreeze cycles (to determine the contribution of in vitro platelet degradation). Plasminogen activator inhibitor-1 activity, plasminogen activator inhibitor-1 antigen, tissue plasminogen activator/plasminogen activator inhibitor-1 complex, plasma clot lysis time, β-thromboglobulin and plasma platelet count were analysed. Platelet α-granule release (plasma β-thromboglobulin) showed a significant association with plasminogen activator inhibitor-1 antigen levels but weak associations with plasminogen activator inhibitor-1 activity and a functional marker of fibrinolysis, clot lysis time. Upon dividing the study population into quartiles based on β-thromboglobulin levels, plasminogen activator inhibitor-1 antigen increased significantly across the quartiles while plasminogen activator inhibitor-1 activity and clot lysis time tended to increase in the 4th quartile only. In the follow-up study, plasma plasminogen activator inhibitor-1 antigen was also significantly influenced by platelet count in a concentration-dependent manner. Plasma plasminogen activator inhibitor-1 antigen levels increased further after complete platelet degradation. Residual platelets in plasma significantly influence plasma plasminogen activator inhibitor-1 antigen levels mainly through release of

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

    Science.gov (United States)

    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.

  1. Human platelet antigen genotyping of platelet donors in southern Brazil.

    Science.gov (United States)

    Merzoni, J; Fagundes, I S; Lunardi, L W; Lindenau, J D-R; Gil, B C; Jobim, M; Dias, V G; Merzoni, L; Sekine, L; Onsten, T G H; Jobim, L F

    2015-10-01

    Human platelet antigens (HPA) are immunogenic structures that result from single nucleotide polymorphisms (SNPs) leading to single amino acid substitutions. This study sought to determine the allele and genotype frequencies of HPA-1, HPA-2, HPA-3, HPA-4, HPA-5 and HPA-15 in platelet donors from the state of Rio Grande do Sul (RS), Brazil, and compare their allele frequencies to those observed in other populations. HPA genotyping was performed by PCR-SSP method. The study sample comprised 201 platelet donors (167 Caucasians and 34 non-Caucasians). Allele 'a' was that most commonly found for HPA-1 to 5 in both groups. The HPA-15ab genotype predominated over homozygous genotypes of this system. Fisher's exact test revealed statistically significant differences for the HPA-5 system, with a greater prevalence of the HPA-5b allele in non-Caucasians. The neighbour-joining method and principal components analysis revealed genetic proximity between our Caucasian group and European populations. We conclude that the allele frequencies of HPA-1 to 5 and HPA-15 found in our Caucasian sample are similar to those reported for European populations. These findings corroborate the ethnic makeup of the population of RS. The higher frequency of the HPA-5b allele found in the non-Caucasian group of our sample suggests the possibility of allosensitization in patients who receive platelet transfusions from genetically incompatible donors.

  2. Platelet-activating factor induces phospholipid turnover, calcium flux, arachidonic acid liberation, eicosanoid generation, and oncogene expression in a human B cell line

    Energy Technology Data Exchange (ETDEWEB)

    Schulam, P.G.; Kuruvilla, A.; Putcha, G.; Mangus, L.; Franklin-Johnson, J.; Shearer, W.T. (Baylor College of Medicine, Houston, TX (USA))

    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.

  3. Platelet count and platelet indices in women with preeclampsia

    Directory of Open Access Journals (Sweden)

    AlSheeha MA

    2016-11-01

    Full Text Available Muneera A AlSheeha,1 Rafi S Alaboudi,1 Mohammad A Alghasham,1 Javed Iqbal,2 Ishag Adam1 1Department of Obstetrics and Gynaecology, College of Medicine, Qassim University, Buriadah, 2Department of Obstetrics and Gynecology, Maternity and Children’s Hospital, Qassim, Kingdom of Saudi Arabia Background: Although the exact pathophysiology of preeclampsia is not completely understood, the utility of different platelets indices can be utilized to predict preeclampsia.Objective: To compare platelet indices, namely platelet count (PC, mean platelet volume (MPV, platelet distribution width (PDW, and PC to MPV ratio in women with preeclampsia compared with healthy controls.Setting: Qassim Hospital, Kingdom of Saudi Arabia.Design: A case–control study. Sixty preeclamptic women were the cases and an equal number of healthy pregnant women were the controls.Results: There was no significant difference in age, parity, and body mass index between the study groups. Sixteen and 44 of the cases were severe and mild preeclampsia, respectively. There was no significant difference in PDW and MPV between the preeclamptic and control women. Both PC and PC to MPV ratios were significantly lower in the women with preeclampsia compared with the controls. There was no significant difference in the PC, PDW, MPV, and PC to MPV ratio when women with mild and severe preeclampsia were compared. Using receiver operating characteristic (ROC curves, the PC cutoff was 248.0×103/µL for diagnosis of preeclampsia (P=0.019; the area under the ROC curve was 62.4%. Binary regression suggests that women with PC <248.010×103/µL were at higher risk of preeclampsia (odds ratio =2.2, 95% confidence interval =1.08–4.6, P=0.03. The PC/MPV cutoff was 31.2 for diagnosis of preeclampsia (P=0.035, the area under the ROC curve was 62.2%.Conclusion: PC <248.010×103/µL and PC to MPV ratio 31.2 are valid predictors of preeclampsia. Keywords: preeclampsia, platelets, PDW, mean platelet

  4. Alterations in plasma membrane promote overexpression and increase of sodium influx through epithelial sodium channel in hypertensive platelets.

    Science.gov (United States)

    Cerecedo, D; Martínez-Vieyra, Ivette; Sosa-Peinado, Alejandro; Cornejo-Garrido, Jorge; Ordaz-Pichardo, Cynthia; Benítez-Cardoza, Claudia

    2016-08-01

    Platelets are small, anucleated cell fragments that activate in response to a wide variety of stimuli, triggering a complex series of intracellular pathways leading to a hemostatic thrombus formation at vascular injury sites. However, in essential hypertension, platelet activation contributes to causing myocardial infarction and ischemic stroke. Reported abnormalities in platelet functions, such as platelet hyperactivity and hyperaggregability to several agonists, contribute to the pathogenesis and complications of thrombotic events associated with hypertension. Platelet membrane lipid composition and fluidity are determining for protein site accessibility, structural arrangement of platelet surface, and response to appropriate stimuli. The present study aimed to demonstrate whether structural and biochemical abnormalities in lipid membrane composition and fluidity characteristic of platelets from hypertensive patients influence the expression of the Epithelial Sodium Channel (ENaC), fundamental for sodium influx during collagen activation. Wb, cytometry and quantitative Reverse Transcription-Polymerase Chain Reaction (qRT-PCR) assays demonstrated ENaC overexpression in platelets from hypertensive subjects and in relation to control subjects. Additionally, our results strongly suggest a key role of β-dystroglycan as a scaffold for the organization of ENaC and associated proteins. Understanding of the mechanisms of platelet alterations in hypertension should provide valuable information for the pathophysiology of hypertension.

  5. The human endogenous circadian system causes greatest platelet activation during the biological morning independent of behaviors.

    Directory of Open Access Journals (Sweden)

    Frank A J L Scheer

    Full Text Available BACKGROUND: Platelets are involved in the thromboses that are central to myocardial infarctions and ischemic strokes. Such adverse cardiovascular events have day/night patterns with peaks in the morning (~9 AM, potentially related to endogenous circadian clock control of platelet activation. The objective was to test if the human endogenous circadian system influences (1 platelet function and (2 platelet response to standardized behavioral stressors. We also aimed to compare the magnitude of any effects on platelet function caused by the circadian system with that caused by varied standardized behavioral stressors, including mental arithmetic, passive postural tilt and mild cycling exercise. METHODOLOGY/PRINCIPAL FINDINGS: We studied 12 healthy adults (6 female who lived in individual laboratory suites in dim light for 240 h, with all behaviors scheduled on a 20-h recurring cycle to permit assessment of endogenous circadian function independent from environmental and behavioral effects including the sleep/wake cycle. Circadian phase was assessed from core body temperature. There were highly significant endogenous circadian rhythms in platelet surface activated glycoprotein (GP IIb-IIIa, GPIb and P-selectin (6-17% peak-trough amplitudes; p ≤ 0.01. These circadian peaks occurred at a circadian phase corresponding to 8-9 AM. Platelet count, ATP release, aggregability, and plasma epinephrine also had significant circadian rhythms but with later peaks (corresponding to 3-8 PM. The circadian effects on the platelet activation markers were always larger than that of any of the three behavioral stressors. CONCLUSIONS/SIGNIFICANCE: These data demonstrate robust effects of the endogenous circadian system on platelet activation in humans--independent of the sleep/wake cycle, other behavioral influences and the environment. The 9 AM timing of the circadian peaks of the three platelet surface markers, including platelet surface activated GPIIb-IIIa, the

  6. [Epidemiology and prevention of anaphylactoid reactions in heart surgery patients].

    Science.gov (United States)

    Trekova, N A; Solovova, L E; Kuznetsov, R V; Asmangulian, E T

    2000-01-01

    A retrospective analysis of the incidence, severity, and causes of anaphylactoid reactions (AR) in 1504 cardiosurgical patients operated on at Research Center of Surgery in 1995-1999 showed that AR occurred in 109 (7.4%) patients: 60% during aortocoronary bypass operations, 27.2% during correction of acquired heart diseases, and 12.8% during correction of congenital heart diseases. Skin symptoms predominated in the structure of AR (59.7%); cardiovascular episodes ranked second (38.5%), and the incidence of pulmonary reactions was lowest (1.8%). The causes of AR during anesthesia and surgery were platelet-rich plasma and fresh-frozen plasma (35.3%), antibiotics (12.1%), protamine (12.1%), myorelaxants (9.9%), colloid plasma substitutes (8.8%), dioxidine (3.3%), heparin (2.2%), aprotinin (1.1%), diazepam (2.2%), and other agents (7.6%). A history of AR and repeated interventions are risk factors of AR. The protocol of AR prevention in cardiosurgical patients includes determination of risk factors, selection of the least hazardous agents, strict adherence to the rate of infusion of histamine-releasing drugs, minimum utilization of donor blood components (platelets and plasma), use of H1 and H2 blockers, corticosteroids (celestone) during premedication and operation. Such treatment helped decrease the severity and incidence of AR in cardiosurgical patients to 4.7%.

  7. Platelet count and platelet indices in women with preeclampsia.

    Science.gov (United States)

    AlSheeha, Muneera A; Alaboudi, Rafi S; Alghasham, Mohammad A; Iqbal, Javed; Adam, Ishag

    2016-01-01

    Although the exact pathophysiology of preeclampsia is not completely understood, the utility of different platelets indices can be utilized to predict preeclampsia. To compare platelet indices, namely platelet count (PC), mean platelet volume (MPV), platelet distribution width (PDW), and PC to MPV ratio in women with preeclampsia compared with healthy controls. Qassim Hospital, Kingdom of Saudi Arabia. A case-control study. Sixty preeclamptic women were the cases and an equal number of healthy pregnant women were the controls. There was no significant difference in age, parity, and body mass index between the study groups. Sixteen and 44 of the cases were severe and mild preeclampsia, respectively. There was no significant difference in PDW and MPV between the preeclamptic and control women. Both PC and PC to MPV ratios were significantly lower in the women with preeclampsia compared with the controls. There was no significant difference in the PC, PDW, MPV, and PC to MPV ratio when women with mild and severe preeclampsia were compared. Using receiver operating characteristic (ROC) curves, the PC cutoff was 248.0×10(3)/µL for diagnosis of pre-eclampsia (P=0.019; the area under the ROC curve was 62.4%). Binary regression suggests that women with PC preeclampsia (odds ratio =2.2, 95% confidence interval =1.08-4.6, P=0.03). The PC/MPV cutoff was 31.2 for diagnosis of preeclampsia (P=0.035, the area under the ROC curve was 62.2%). PC preeclampsia.

  8. Platelet activation by extracellular matrix proteins in haemostasis and thrombosis.

    Science.gov (United States)

    Watson, Steve P

    2009-01-01

    The prevention of excessive blood loss to avoid fatal haemorrhage is a pivotal process for all organisms possessing a circulatory system. Increased circulating blood volume and pressure, as required in larger animals, make this process all the more important and challenging. It is essential to have a powerful and rapid system to detect damage and generate an effective seal, and which is also exquisitely regulated to prevent unwanted, excessive or systemic activation so as to avoid blockage of vessels. Thus, a highly specialised and efficient haemostatic system has evolved that consists of cellular (platelets) and protein (coagulation factors) components. Importantly, this is able to support haemostasis in both the low shear environment of the venous system and the high shear environment of the arterial system. Endothelial cells, lining the entire circulation system, play a crucial role in the delicate balance between activation and inhibition of the haemostatic system. An intact and healthy endothelium supports blood flow by preventing attachment of cells and proteins which is required for initiation of coagulation and platelet activation. Endothelial cells produce and release the two powerful soluble inhibitors of platelet activation, nitric oxide and prostacyclin, and express high levels of CD39 which rapidly metabolises the major platelet feedback agonist, ADP. This antithrombotic environment however can rapidly change following activation or removal of endothelial cells through injury or rupture of atherosclerotic plaques. Loss of endothelial cells exposes the subendothelial extracellular matrix which creates strong signals for activation of the haemostatic system including powerful platelet adhesion and activation. Quantitative and qualitative changes in the composition of the subendothelial extracellular matrix influence these prothrombotic characteristics with life threatening thrombotic and bleeding complications, as illustrated by formation of

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1984-11-01

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

  10. Application of platelet-rich plasma and platelet-rich fibrin in fat grafting: basic science and literature review.

    Science.gov (United States)

    Liao, Han-Tsung; Marra, Kacey G; Rubin, J Peter

    2014-08-01

    Due to the natural properties of fat, fat grafting remains a popular procedure for soft tissue volume augmentation and reconstruction. However, clinical outcome varies and is technique dependent. Platelet-rich plasma (PRP) contains α-granules, from which multiple growth factors such as platelet-derived growth factor, transforming growth factor-β, vascular endothelial growth factor, and epidermal growth factor can be released after activation. In recent years, the scope of PRP therapies has extended from bone regeneration, wound healing, and healing of musculoskeletal injuries, to enhancement of fat graft survival. In this review, we focus on the definition of PRP, the different PRP preparation and activation methods, and growth factor concentrations. In addition, we discuss possible mechanisms for the role of PRP in fat grafting by reviewing in vitro studies with adipose-derived stem cells, preadipocytes, and adipocytes, and preclinical and clinical research. We also review platelet-rich fibrin, a so-called second generation PRP, and its slow-releasing biology and effects on fat grafts compared to PRP in both animal and clinical research. Finally, we provide a general foundation on which to critically evaluate earlier studies, discuss the limitations of previous research, and direct plans for future experiments to improve the optimal effects of PRP in fat grafting.

  11. cAMP signaling in blood platelets - old friends and new players.

    Directory of Open Access Journals (Sweden)

    Zaher eRaslan

    2015-11-01

    Full Text Available Atherothrombosis, the pathology underlying numerous cardiovascular diseases, is a major cause of death globally. Hyperactive blood platelets play a key role in the atherothrombotic process through the release of inflammatory mediators and formation of thrombi. In healthy blood vessels, excessive platelet activation is restricted by endothelial-derived prostacyclin (PGI2 through cyclic adenosine-5’-monophosphate (cAMP and protein kinase A (PKA-dependent mechanisms. Elevation in intracellular cAMP is associated with the control of a number of distinct platelet functions including actin polymerisation, granule secretion, calcium mobilisation and integrin activation. Unfortunately, in atherosclerotic disease the protective effects of cAMP are compromised, which may contribute to pathological thrombosis. The cAMP signalling network in platelets is highly complex with the presence of multiple isoforms of adenylyl cyclase (AC, PKA and phosphodiesterases (PDE. However, a precise understanding of the relationship between specific AC, PKA and PDE isoforms, and how individual signalling substrates are targeted to control distinct platelet functions is still lacking. In other cells types, compartmentalisation of cAMP signalling has emerged as a key mechanism to allow precise control of specific cell functions. A-kinase anchoring proteins (AKAPs play an important role in this spatiotemporal regulation of cAMP signalling networks. Evidence of AKAP-mediated compartmentalisation of cAMP signalling in blood platelets has begun to emerge and is providing new insights into the regulation of platelet function. Dissecting the mechanisms that allow cAMP to control excessive platelet activity without preventing effective haemostasis may unleash the possibility of therapeutic targeting of the pathway to control unwanted platelet activity.

  12. Recent advancements in erythrocytes, platelets, and albumin as delivery systems.

    Science.gov (United States)

    Xu, Peipei; Wang, Ruju; Wang, Xiaohui; Ouyang, Jian

    2016-01-01

    In the past few years, nanomaterial-based drug delivery systems have been applied to enhance the efficacy of therapeutics and to alleviate negative effects through the controlled delivery of targeting and releasing agents. However, few drug carriers can achieve high targeting efficacy, even when targeting modalities and surface markers are introduced. Immunological problems have also limited their wide applications. Biological drug delivery systems, such as erythrocytes, platelets, and albumin, have been extensively investigated because of their unique properties. In this review, erythrocytes, platelets, and albumin are described as efficient drug delivery systems. Their properties, applications, advantages, and limitations in disease treatment are explained. This review confirms that these systems can be used to facilitate a specific, biocompatible, and smart drug delivery.

  13. Experimental Study on Reaction Energy Release Characteristics of Hydrocarbon and Chlorine Trifluoride%三氟化氯与碳氢燃料反应放能试验研究

    Institute of Scientific and Technical Information of China (English)

    高洪泉; 卢芳云; 王少龙; 罗永锋; 闫华; 刘志勇

    2011-01-01

    Using a designed experimental device,explosion experiments of hydrocarbon with chlorine trifluoride in confined space were carried out,based on the analysis of the hydrocarbon and chlorine trifluoride reaction mechanism. The energy released from the reaction of hydrocarbon and chlorine trifluoride without oxygen was calculated based on experimental results. Results show that (1) The reaction of hydrocarbon and chlorine trifluoride accompanies an intense release of great deal of energy,so that part of the hydrocarbon is vaporized and dispersed,a violent deflagrating would be ignited once the vaporized hydrocarbon be mixed with the air. (2) The TNT equivalence of the explosion reaction of hydrocarbon and chlorine trifluoride without oxygen is about 1.8.%在对三氟化氯与碳氢燃料反应机理进行分析的基础上,进行了密闭环境下三氟化氯与碳氢燃料的反应放能试验研究.结果表明:三氟化氯与碳氢燃料可以发生剧烈反应,释放大量的能量,将碳氢燃料部分雾化并喷出密闭空间,激活的碳氢燃料一旦接触空气,便诱发碳氢燃料的剧烈爆燃;在无氧条件下,三氟化氯与碳氢燃料爆炸反应所释放的能量相当于1.8倍TNT当量.

  14. The automation of routine light transmission platelet aggregation

    Science.gov (United States)

    Lawrie, A S; Kobayashi, K; Lane, P J; Mackie, I J; Machin, S J

    2014-01-01

    Introduction The investigation of platelet function by aggregometry requires specialist equipment and is labour intensive. We have developed an automated platelet aggregation method on a routine coagulation analyser. Methods We used a CS-2000i (Sysmex) with prototype software to perform aggregation in platelet-rich plasma (PRP), using the following agonists: ADP (0.5–10 μm), epinephrine (0.5–10 μm), collagen (0.5–10 mg/μL), ristocetin (0.75–1.25 mg/mL) and arachidonic acid (0.12–1.0 mm). Platelet agonists were from Hyphen Biomed, and an AggRAM aggregometer (Helena Biosciences) was used as the reference instrument. Results CS-2000i reaction cuvette stirrer speed was found to influence reaction sensitivity and was optimized to 800 rpm. There were no clinically significant changes in aggregation response when the PRP platelet count was 150–480 x 109/L, but below this there were changes in the maximum amplitude (MA) and slope (rate). Dose response with each of the agonists was comparable between CS-2000i and an AggRAM aggregometer and normal subjects receiving antiplatelet drugs. Aggregation imprecision was similar on both the CS-2000i and AggRAM systems, with a cv for 2–5 μm ADP MA and slope varying between 3–12%. Conclusion Our preliminary studies indicated that optimal sensitivity using the CS-2000i was obtained with a reaction cuvette stirrer speed of 800 rpm and a PRP platelet count of 200–300 x 109/L; aggregation with a PRP count <100 x 109/L showed poor sensitivity. Imprecision and detection of antiplatelet drug effects was similar between the CS-2000i and AggRAM. These data demonstrate that CS-2000i is comparable to a stand-alone aggregometer, although CS-2000i has the advantages of walk-away technology and also required a smaller sample volume than the AggRAM (44% less). PMID:24237750

  15. Platelets: crossroads of immunity and hemostasis.

    Science.gov (United States)

    Jenne, Craig N

    2014-07-31

    In this issue of Blood, Koupenova and colleagues report that platelets express functional TOLL-like receptor 7 (TLR7) and contribute to host survival during viral infection. Through a series of experiments utilizing mice deficient for TLR7 together with adoptive transfer of wild-type platelets, Koupenova et al demonstrate that platelets specifically respond to viral analogs and intact virus, leading to platelet activation and binding to various leukocyte subsets. Perhaps most importantly, this platelet activation appears absolutely essential for host survival during infection with some viral pathogens such as encephalomyocarditis virus (EMCV).

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  18. Characteristics of the THERAFLEX UV-Platelets pathogen inactivation system - an update.

    Science.gov (United States)

    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. Suppressive effect of CORM-2 on LPS-induced platelet activation by glycoprotein mediated HS1 phosphorylation interference.</