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Articoli di riviste sul tema "Platelet factor 4"

Autore: Grafiati

Pubblicato: 4 giugno 2021

Ultima modifica: 30 gennaio 2023

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1

Shimizu, T., Y. Ishikawa, Y. Morishima, T. Fukuda e K. Kato. "Platelet factor 4 release from the platelets stored in platelet concentrates". Transfusion 25, n. 5 (settembre 1985): 420–23. http://dx.doi.org/10.1046/j.1537-2995.1985.25586020114.x.

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2

CAPITANIO, A., S. NIEWIAROWSKI, B. RUCINSKI, G. TUSZYNSKI, C. CIERNIEWSKI, D. HERSHOCK e E. KORNECKI. "Interaction of platelet factor 4 with human platelets". Biochimica et Biophysica Acta (BBA) - General Subjects 839, n. 2 (17 aprile 1985): 161–73. http://dx.doi.org/10.1016/0304-4165(85)90033-9.

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3

O'Brien, J. R. "PLATELET FACTOR 4 (PF 4) AND THE PLATELET MEMBRANE". Acta Medica Scandinavica 191, S525 (24 aprile 2009): 65–66. http://dx.doi.org/10.1111/j.0954-6820.1972.tb05793.x.

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4

Sottile, Jane, Deane F. Mosher, Jan Fullenweider e James N. George. "Human Platelets Contain mRNA Transcripts for Platelet Factor 4 and Actin". Thrombosis and Haemostasis 62, n. 04 (1989): 1100–1102. http://dx.doi.org/10.1055/s-0038-1647125.

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SummaryRNAs from a number of cells, including platelets, were analyzed by Northern blotting for the presence of transcripts to four platelet proteins - actin, thrombospondin, fibronectin, and platelet factor 4. RNA from platelets contains considerable amounts of mRNA for platelet factor 4, easily detectable mRNA for actin, and traces of mRNA for thrombospondin. mRNA for platelet factor 4 was not detected in human lymphocytes or in any of 5 human cell lines.

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5

Cowan, S. W., E. N. Bakshi, K. J. Machin e N. W. Isaacs. "Binding of heparin to human platelet factor 4". Biochemical Journal 234, n. 2 (1 marzo 1986): 485–88. http://dx.doi.org/10.1042/bj2340485.

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Platelet factor 4 is a small protein (Mr 7756) from the alpha-granules of blood platelets which binds strongly to and neutralizes the anticoagulant properties of heparin. From an analysis of X-ray crystallographic data a model for the binding of platelet factor 4 to heparin is proposed.

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6

Dickhout, Annemiek, Bibian M. E. Tullemans, Johan W. M. Heemskerk, Victor L. J. L. Thijssen, Marijke J. E. Kuijpers e Rory R. Koenen. "Galectin-1 and platelet factor 4 (CXCL4) induce complementary platelet responses in vitro". PLOS ONE 16, n. 1 (7 gennaio 2021): e0244736. http://dx.doi.org/10.1371/journal.pone.0244736.

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Galectin-1 (gal-1) is a carbohydrate-binding lectin with important functions in angiogenesis, immune response, hemostasis and inflammation. Comparable functions are exerted by platelet factor 4 (CXCL4), a chemokine stored in the α-granules of platelets. Previously, gal-1 was found to activate platelets through integrin αIIbβ3. Both gal-1 and CXCL4 have high affinities for polysaccharides, and thus may mutually influence their functions. The aim of this study was to investigate a possible synergism of gal-1 and CXCL4 in platelet activation. Platelets were treated with increasing concentrations of gal-1, CXCL4 or both, and aggregation, integrin activation, P-selectin and phosphatidyl serine (PS) exposure were determined by light transmission aggregometry and by flow cytometry. To investigate the influence of cell surface sialic acid, platelets were treated with neuraminidase prior to stimulation. Gal-1 and CXCL4 were found to colocalize on the platelet surface. Stimulation with gal-1 led to integrin αIIbβ3 activation and to robust platelet aggregation, while CXCL4 weakly triggered aggregation and primarily induced P-selectin expression. Co-incubation of gal-1 and CXCL4 potentiated platelet aggregation compared with gal-1 alone. Whereas neither gal-1 and CXCL4 induced PS-exposure on platelets, prior removal of surface sialic acid strongly potentiated PS exposure. In addition, neuraminidase treatment increased the binding of gal-1 to platelets and lowered the activation threshold for gal-1. However, CXCL4 did not affect binding of gal-1 to platelets. Taken together, stimulation of platelets with gal-1 and CXCL4 led to distinct and complementary activation profiles, with additive rather than synergistic effects.

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7

Day, H. James, H. Stormorken e H. Holmsen. "Subcellular Localization of Platelet Factor 3 and Platelet Factor 4". Scandinavian Journal of Haematology 10, n. 4 (24 aprile 2009): 254–60. http://dx.doi.org/10.1111/j.1600-0609.1973.tb00069.x.

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8

Leavitt, Andrew D. "What for platelet factor 4?" Blood 110, n. 4 (15 agosto 2007): 1090. http://dx.doi.org/10.1182/blood-2007-05-091363.

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9

Robinson, C. "Recombinant Human Platelet Factor 4". Drugs of the Future 20, n. 2 (1995): 148. http://dx.doi.org/10.1358/dof.1995.020.02.284334.

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10

Lorenz, R., e M. Brauer. "Platelet factor 4 (PF 4) in septicaemia". Infection 16, n. 5 (settembre 1988): 273–76. http://dx.doi.org/10.1007/bf01645070.

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11

Gjesdal, K., e A. F. Abrahamsen. "Platelet Consumption and Plasma Concentration of Platelet Factor 4 (PF-4)". Scandinavian Journal of Haematology 17, n. 1 (24 aprile 2009): 5–9. http://dx.doi.org/10.1111/j.1600-0609.1976.tb02834.x.

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12

O'Brien, J. R. "PLATELET FACTOR 3 (PF 3) AND PLATELET FACTOR 4 (PF 4) AS A GUIDE TO PLATELET MEMBRANE STRUCTURE". Acta Medica Scandinavica 191, S525 (24 aprile 2009): 87–88. http://dx.doi.org/10.1111/j.0954-6820.1972.tb05799.x.

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13

Levine, SP, LK Knieriem e MA Rager. "Platelet factor 4 and the platelet secreted proteoglycan: immunologic characterization by crossed immunoelectrophoresis". Blood 75, n. 4 (15 febbraio 1990): 902–10. http://dx.doi.org/10.1182/blood.v75.4.902.902.

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Abstract Platelet factor 4 (PF4) is a hydrophobic, alpha-granule protein with potent antiheparin activity. It also binds to a chondroitin sulfate- containing proteoglycan (PG) isolated from platelets. In order to evaluate further the relationship between PF4 and the chondroitin sulfate-containing proteoglycan in resting platelets, the PF4-binding proteoglycan from human platelets has been purified using purified PF4 as an affinity ligand and used to prepare polyclonal antiserum. Two antisera have been characterized: one reacts primarily with chondroitin sulfate (CS), the other reacts with the protein core of the platelet proteoglycan after chondroitinase AC digestion. PF4 and PG core protein antigen are present in separate, dissimilar precipitin arcs when triton- solubilized platelets are analyzed by crossed immunoelectrophoresis using polyclonal antisera to purified PF4 and PG. PF4 was demonstrated in a complex with a separate chondroitin sulfate antigen by crossed immunoelectrophoresis (CIE) experiments in which either anti-PF4 or anti-CS antisera was incorporated in the intermediate gel. Both the PF4- chondroitin sulfate complex and the proteoglycan are secreted from platelets when fresh, washed human platelets are stimulated by human alpha-thrombin. This second antigen may represent the PG after posttranslational modification of a precursor form of the proteoglycan.

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14

Levine, SP, LK Knieriem e MA Rager. "Platelet factor 4 and the platelet secreted proteoglycan: immunologic characterization by crossed immunoelectrophoresis". Blood 75, n. 4 (15 febbraio 1990): 902–10. http://dx.doi.org/10.1182/blood.v75.4.902.bloodjournal754902.

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Abstract (sommario):

Platelet factor 4 (PF4) is a hydrophobic, alpha-granule protein with potent antiheparin activity. It also binds to a chondroitin sulfate- containing proteoglycan (PG) isolated from platelets. In order to evaluate further the relationship between PF4 and the chondroitin sulfate-containing proteoglycan in resting platelets, the PF4-binding proteoglycan from human platelets has been purified using purified PF4 as an affinity ligand and used to prepare polyclonal antiserum. Two antisera have been characterized: one reacts primarily with chondroitin sulfate (CS), the other reacts with the protein core of the platelet proteoglycan after chondroitinase AC digestion. PF4 and PG core protein antigen are present in separate, dissimilar precipitin arcs when triton- solubilized platelets are analyzed by crossed immunoelectrophoresis using polyclonal antisera to purified PF4 and PG. PF4 was demonstrated in a complex with a separate chondroitin sulfate antigen by crossed immunoelectrophoresis (CIE) experiments in which either anti-PF4 or anti-CS antisera was incorporated in the intermediate gel. Both the PF4- chondroitin sulfate complex and the proteoglycan are secreted from platelets when fresh, washed human platelets are stimulated by human alpha-thrombin. This second antigen may represent the PG after posttranslational modification of a precursor form of the proteoglycan.

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15

Hayashi, Nobana, Junichi Chihara, Yohnosuke Kobayashi, Tomokazu Kakazu, Dai Kurachi, Takahiro Yamamoto e Shigenori Nakajima. "Effect of Platelet-Activating Factor and Platelet Factor 4 on Eosinophil Adhesion". International Archives of Allergy and Immunology 104, n. 1 (1994): 57–59. http://dx.doi.org/10.1159/000236754.

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16

Ryo, Ryukichi, Mutsumi Yasunaga, Katsuyasu Saigo e Nobuo Yamaguchi. "Megakaryocytic Leukemia and Platelet Factor 4". Leukemia & Lymphoma 8, n. 4-5 (gennaio 1992): 327–36. http://dx.doi.org/10.3109/10428199209051011.

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17

Williams, R. Taylor, Lakshmi V. Damaraju, Mary Ann Mascelli, Elliot S. Barnathan, Robert M. Califf, Maarten L. Simoons, Efthymios N. Deliargyris e David C. Sane. "Anti-Platelet Factor 4/Heparin Antibodies". Circulation 107, n. 18 (13 maggio 2003): 2307–12. http://dx.doi.org/10.1161/01.cir.0000066696.57519.af.

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18

&NA;. "Rapid Heparin/Platelet Factor 4 Test". Nurse Practitioner 30, n. 1 (gennaio 2005): 62. http://dx.doi.org/10.1097/00006205-200501000-00009.

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19

Mammen, Eberhard. "Platelet Factor 4 in Cardiovascular Disease". Seminars in Thrombosis and Hemostasis 30, n. 03 (29 luglio 2004): 269–71. http://dx.doi.org/10.1055/s-2004-831038.

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20

Slungaard, Arne. "Platelet factor 4: a chemokine enigma". International Journal of Biochemistry & Cell Biology 37, n. 6 (giugno 2005): 1162–67. http://dx.doi.org/10.1016/j.biocel.2004.12.003.

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21

Villanueva, German B., Nancy Allen e Daniel Walz. "Circular dichroism of platelet factor 4". Archives of Biochemistry and Biophysics 261, n. 1 (febbraio 1988): 170–74. http://dx.doi.org/10.1016/0003-9861(88)90115-4.

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22

Chen, Jinhui, Gang Liu, Yan Hong, Jing Han, Zhe Yang, Yanping Yang, Hong Li, Shumin Wang, Lili Jue e Qi Wang. "Regulation of Atherosclerosis by Toll-Like Receptor 4 Induced by Serum Amyloid 1: A Systematic In Vitro Study". BioMed Research International 2022 (15 settembre 2022): 1–14. http://dx.doi.org/10.1155/2022/4887593.

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The objective of this study was to investigate the effects of serum amyloid 1 (SAA1) on activation of endothelial cells, formation of foam cells, platelet aggregation, and monocyte/platelet adhesion to endothelial cells. The effect of SAA1 on the inflammatory activation of endothelial cells was investigated by detecting the expression of inflammatory factors and adhesion molecules. The role of SAA1 in formation of foam cells was verified by detecting lipid deposition and expression of molecules related to the formation of foam cells. After platelets were stimulated by SAA1, the aggregation rate was evaluated to determine the effect of SAA1 on platelet aggregation. Monocytes/platelets were cocultured with human umbilical vein endothelial cells (HUVECs) pretreated with or without SAA1 to determine whether SAA1 affected monocyte/platelet adhesion to endothelial cells. By inhibiting toll-like receptor 4 (TLR4) function, we further identified the role of TLR4 signaling in SAA1-mediated endothelial inflammatory activation, foam-cell formation, and monocyte/platelet adhesion to HUVECs. SAA1 significantly increased the expression of adhesion molecules and inflammatory factors in HUVECs. Moreover, SAA1 also promoted lipid deposition and the expression of inflammatory factors and low-density lipoprotein receptor-1 (LOX-1) in THP-1-derived macrophages. In addition, SAA1 induced platelet aggregation and enhanced monocyte/platelet adhesion to HUVECs. However, the TLR4 antagonist significantly inhibited SAA1-induced endothelial cell activation, foam-cell formation, and monocyte/platelet adhesion to HUVECs and downregulated the expression of myeloid differentiation factor 88 (MyD88), phosphor-inhibitor of nuclear factor κB kinase subunit α/β (P-IKKα/β), phospho-inhibitor of nuclear factor κB subunit α (P-IKBα), and phosphorylation of nuclear transcription factor-κB p65 (P-p65) in SAA1-induced HUVECs and THP-1 cells. Conclusively, it is speculated that SAA1 promotes atherosclerosis through enhancing endothelial cell activation, platelet aggregation, foam-cell formation, and monocyte/platelet adhesion to endothelial cells. These biological functions of SAA1 may depend on the activation of TLR4-related nuclear factor-kappa B (NF-κB) signaling pathway.

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23

Campbell, Robert A., Thomas H. Fischer e Alisa S. Wolberg. "Rehydrated, Lyophilized Platelets Generate Thrombin in the Presence of Recombinant Factor VIIa." Blood 106, n. 11 (16 novembre 2005): 4057. http://dx.doi.org/10.1182/blood.v106.11.4057.4057.

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Abstract The anti-bleeding therapy, recombinant factor VIIa (rFVIIa), is thought to bind to the platelet’s surface and increase thrombin generation in hemophilia. However, high plasma levels of rFVIIa are required, in part, due to the weak binding of rFVIIa to platelets. We hypothesized that the efficacy of the therapy could be improved by administering rFVIIa already bound to platelets. A recently described protocol involving pretreatment of platelets with paraformaldehyde permits platelets to be lyophilized while preserving many platelet functions. Such platelets could be used for binding rFVIIa ex vivo and then administered to hemophilic patients during a bleeding event. In this study, we have characterized the ability of reconstituted, lyophilized (RL) platelets to support thrombin generation under normal and hemophilic conditions and in the presence of rFVIIa. First, freshly-isolated (control) or RL platelets were incubated with factors IXa, VIII(a), X, V and II in the presence of 3 mM CaCl2 and assayed for thrombin generation. In these assays, both freshly-isolated and RL platelets supported thrombin generation (1.15x10−4 +/− 5.37x10−5 mOD/min2/platelet and 8.46x10−3 +/− 4.78x10−3 mOD/min2/platelet, respectively). In the absence of factor IX (hemophilia B), thrombin generation was significantly reduced on both freshly-isolated and RL platelets (4.19x10−6 +/− 4.50x10−6 mOD/min2/platelet and 8.25x10−4 +/− 1.13x10−6 mOD/min2/platelet, respectively). Interestingly, RL platelets supported 10 – 100-fold higher thrombin generation rates than fresh thrombin-activated platelets. Second, we examined the activity of rFVIIa on RL platelets in the absence of factors IX and VIII. RFVIIa increased thrombin generation on RL platelets in a rFVIIa-concentration dependent manner (between 1nM and 150nM), similar to that seen when using fresh platelets. An inhibitory anti-tissue factor (TF) antibody did not affect rFVIIa-mediated thrombin generation on RL platelets, indicating that the activity of rFVIIa on RL platelets is independent of TF. Finally, we examined the effect of different platelet agonists (thrombin, convulxin, and A23187) on fresh and RL platelets. When fresh platelets are stimulated with A23187 or co-stimulated with thrombin and convulxin, they become more procoagulant than platelets activated with thrombin alone. However, stimulation of RL platelets with A23187 or co-stimulation with thrombin and convulxin did not increase thrombin generation versus thrombin alone. RL platelets stimulated with thrombin, alone, had 3.1-fold higher activity than thrombin- and convulxin-costimulated fresh platelets, but 1.4-fold lower activity than A23187-stimulated fresh platelets. These data suggest that RL platelets are in a maximally active state prior to the addition of platelet agonists. We conclude that RL platelets are procoagulant and can support rFVIIa-mediated thrombin generation in the absence of factor IX. We hypothesize that co-administration of RL platelets with rFVIIa may increase the efficacy of rFVIIa treatment.

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24

Ren, Qiansheng, Christian Wimmer, Michael C. Chicka, Shaojing Ye, Yi Ren, Frederick M. Hughson e Sidney W. Whiteheart. "Munc13-4 is a limiting factor in the pathway required for platelet granule release and hemostasis". Blood 116, n. 6 (12 agosto 2010): 869–77. http://dx.doi.org/10.1182/blood-2010-02-270934.

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Abstract Activation-dependent platelet granule release is mediated by integral membrane proteins called soluble N-ethylmaleimide–sensitive fusion protein attachment protein receptors (SNAREs) and their regulators; however, the mechanisms for this process are ill-defined. To further characterize platelet secretion, we analyzed the function of platelets from Unc13dJinx mice. Platelets from these animals lack the putative vesicle priming factor, Munc13-4, and have a severe secretion defect. Release from dense granules was completely ablated and that from α-granules and lysosomes was severely compromised. Unc13dJinx platelets showed attenuated aggregation and, consequently, Unc13dJinx mice had prolonged tail-bleeding times. The secretion defect was not due to altered expression of SNAREs or SNARE regulators, defective granule biogenesis, or faulty platelet activation. The defective release could be rescued by adding recombinant Munc13-4 to permeabilized Unc13dJinx platelets. In wild-type mouse platelets, Munc13-4 levels were lower than those of SNAREs suggesting that Munc13-4 could be a limiting component of the platelets' secretory machinery. Consistently, Munc13-4 levels directly correlated with the extent of granule release from permeabilized platelets and from intact, heterozygous Unc13dJinx platelets. These data highlight the importance of Munc13-4 in platelets and indicate that it is a limiting factor required for platelet secretion and hemostasis.

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25

Haselton, F. R., e J. S. Alexander. "Platelets and a platelet-released factor enhance endothelial barrier". American Journal of Physiology-Lung Cellular and Molecular Physiology 263, n. 6 (1 dicembre 1992): L670—L678. http://dx.doi.org/10.1152/ajplung.1992.263.6.l670.

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The role of platelets in the maintenance of endothelial barrier is examined in an in vitro model of the microvasculature. Human platelets (6,000/microliters) perfused through a cell column of endothelial-covered microcarriers decrease paracellular permeability of sodium fluorescein (mol wt 342) to 63% of baseline values. This effect is reversible and a second application and removal of platelets produces a similar response. This effect occurs within 5 min and reverses within 10 min after platelet removal. The reduction in permeability is not due to mechanical obstruction of endothelial junctions, since the number of recirculating platelets is not reduced and releasate from unstimulated 2-h platelet incubations also decreases permeability. Releasate from platelets stimulated with 0.1 U/ml of thrombin for 15 min have the same permeability reducing effect. In this system, the platelet factors serotonin (10(-3) M) and ADP (10(-4) M) have no effect on permeability. However, the platelet factors adenosine (10(-4) M), ATP (10(-5) M), and beta-agonists decrease permeability. None of these appear to account for platelet permeability activity, since activity is not blocked by agents directed against these mediators (adenosine deaminase, apyrase, 8-phenyltheophylline, or propranolol). The active factor(s) is stable at -20 degrees C, heat stable, sensitive to trypsin, and has an apparent molecular weight > 100. We conclude that unstimulated platelets release a factor(s) that enhances endothelial barrier in vitro and may be important in maintenance of the normal in vivo barrier.

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26

Barnes, J. L., K. A. Woodruff, S. P. Levine e H. E. Abboud. "Inhibition of mesangial cell proliferation by platelet factor 4." Journal of the American Society of Nephrology 7, n. 7 (luglio 1996): 991–98. http://dx.doi.org/10.1681/asn.v77991.

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Platelet factor 4(PF4), an abundant platelet secretory product, is a strong candidate for modulating glomerular pathology. Because PF4 might be released from platelets and influence intrinsic cell growth during glomerular injury, the effect of PF4 on fetal calf serum- and platelet-derived growth factor (PDGF)-induced mesangial cell mitogenesis was examined. Mitogenesis was measured as the amount of 3H-thymidine incorporated into acid-precipitable material as well as by autoradiography. The effect of PF4 on mesangial cell expression of mRNA for PDGF A chain and transforming growth factor-beta (TGF-beta 1) was also examined. Fetal calf serum (10%)- and PDGF (10 ng/mL)-stimulated increases in mesangial cell 3H-thymidine incorporation were inhibited by incremental concentrations of PF4 (1 to 25 micrograms/mL) showing a maximum reduction of approximately 80% at 25 micrograms/mL of PF4. PF4 was effective when added 24 h before and 1, 4, and 8 h, but not 16 h after the addition of PDGF, indicating that inhibition occurred at delayed events in cell-cycle regulation. PF4 inhibited PDGF-induced increments in mRNA encoding PDGF A chain and TGF-beta 1. Also, PF4 did not interfere with PDGF receptor binding. The results of this study show that PF4 is a negative regulator of mesangial cell proliferation and suggest an interference in cell growth by pathways associated with modulation of the autocrine growth factors PDGF and TGF-beta 1.

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27

Jayachandran, Muthuvel, Antonio Sanzo, Whyte G. Owen e Virginia M. Miller. "Estrogenic regulation of tissue factor and tissue factor pathway inhibitor in platelets". American Journal of Physiology-Heart and Circulatory Physiology 289, n. 5 (novembre 2005): H1908—H1916. http://dx.doi.org/10.1152/ajpheart.01292.2004.

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Oral estrogen treatment increases thrombotic risk. Tissue factor (TF), tissue factor pathway inhibitor (TFPI), and platelet interaction with leukocytes are important determinants of thrombogenesis. Therefore, the present study was designed to define and compare platelet TF and TFPI mRNA and adhesion protein expression in platelets derived from animals treated with different types of oral estrogens. Ovariectomized pigs were treated with 17β-estradiol (2 mg/day), conjugated equine estrogen (CEE; 0.625 mg/day), or raloxifene (60 mg/day) for 4 wk. Compared with intact animals, ovariectomy and treatment differentially affected populations of leukocytes: neutrophils decreased whereas lymphocytes increased significantly 4 wk after ovariectomy and with 17β-estradiol and CEE treatments; eosinophils increased only with 17β-estradiol treatment. Content of TF protein increased in platelets from 17β-estradiol- and raloxifene-treated pigs, whereas TF mRNA was detected only in platelets from 17β-estradiol- and CEE treated pigs. TFPI mRNA increased in platelets after ovariectomy and estrogen treatment. Only a trace of TFPI protein was detected, but a higher-molecular-mass protein was observed in all treatment groups. Expression of CD40 and CD40 ligand increased with ovariectomy and decreased with 17β-estradiol and CEE treatments more than with raloxifene. The ratio of activated to basal P-selectin expression decreased with ovariectomy and increased with raloxifene treatments. These results suggest that estrogenic formulations may affect individual thrombotic risk by different mechanisms that regulate TF and platelet-leukocytic interactions. These studies provide the rationale for evaluation of interactions among platelets and TF and TFPI expression on thrombin generation during estrogen treatment in humans.

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Uhlin-Hansen, L., D. Langvoll, T. Wik e SO Kolset. "Blood platelets stimulate the expression of chondroitin sulfate proteoglycan in human monocytes". Blood 80, n. 4 (15 agosto 1992): 1058–65. http://dx.doi.org/10.1182/blood.v80.4.1058.1058.

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Abstract Mononuclear phagocytes synthesize chondroitin sulfate proteoglycan (CSPG), which is constitutively secreted. Because mononuclear phagocytes are known to interact with blood platelets, the effect of platelets on the release of CSPG in cultured human monocytes was investigated. After 6 days in vitro, the monocytes were supplied with fresh medium with different additions and subsequently exposed to [35S]sulfate for 24 hours before the medium fractions were harvested and analyzed for content of [35S]CSPG. Indirect evidence for the release of stimulatory factors from blood platelets was found when the addition of medium containing 50% serum made from platelet-rich plasma increased the expression of [35S]CSPG almost sevenfold compared with serum-free medium, whereas medium containing 50% serum made from platelet-depleted plasma increased the expression of [35S]CSPG about fourfold. Further, direct evidence for the stimulatory effect of platelets was found as the addition of autologous platelets to serum- free medium increased the expression of [35S]CSPG about threefold, and addition of supernatant from a corresponding number of thrombin- stimulated platelets was almost as efficient. The effect of five different platelet-derived factors (which are all present in serum) was investigated. Both platelet-derived growth factor (PDGF), platelet factor 4 (PF 4), and prostaglandin E2 (PGE2) used in physiologic concentrations were found to stimulate the expression of [35S]CSPG twofold to threefold, whereas transforming growth factor-beta had a slight inhibitory effect. 12-Hydroxyeicosatetraenoic acid had no significant effect on the expression of [35S]CSPG. Further evidence for the stimulatory effect of PDGF, PF 4, and PGE2 was found as serum depleted of these factors had significantly less stimulatory effect than control serum. The increased incorporation of [35S]sulfate into [35S]CSPG in cultures stimulated with serum or platelet-derived factors was not due to differences in molecular size or extent of sulfation of the proteoglycan molecules.

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Uhlin-Hansen, L., D. Langvoll, T. Wik e SO Kolset. "Blood platelets stimulate the expression of chondroitin sulfate proteoglycan in human monocytes". Blood 80, n. 4 (15 agosto 1992): 1058–65. http://dx.doi.org/10.1182/blood.v80.4.1058.bloodjournal8041058.

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Mononuclear phagocytes synthesize chondroitin sulfate proteoglycan (CSPG), which is constitutively secreted. Because mononuclear phagocytes are known to interact with blood platelets, the effect of platelets on the release of CSPG in cultured human monocytes was investigated. After 6 days in vitro, the monocytes were supplied with fresh medium with different additions and subsequently exposed to [35S]sulfate for 24 hours before the medium fractions were harvested and analyzed for content of [35S]CSPG. Indirect evidence for the release of stimulatory factors from blood platelets was found when the addition of medium containing 50% serum made from platelet-rich plasma increased the expression of [35S]CSPG almost sevenfold compared with serum-free medium, whereas medium containing 50% serum made from platelet-depleted plasma increased the expression of [35S]CSPG about fourfold. Further, direct evidence for the stimulatory effect of platelets was found as the addition of autologous platelets to serum- free medium increased the expression of [35S]CSPG about threefold, and addition of supernatant from a corresponding number of thrombin- stimulated platelets was almost as efficient. The effect of five different platelet-derived factors (which are all present in serum) was investigated. Both platelet-derived growth factor (PDGF), platelet factor 4 (PF 4), and prostaglandin E2 (PGE2) used in physiologic concentrations were found to stimulate the expression of [35S]CSPG twofold to threefold, whereas transforming growth factor-beta had a slight inhibitory effect. 12-Hydroxyeicosatetraenoic acid had no significant effect on the expression of [35S]CSPG. Further evidence for the stimulatory effect of PDGF, PF 4, and PGE2 was found as serum depleted of these factors had significantly less stimulatory effect than control serum. The increased incorporation of [35S]sulfate into [35S]CSPG in cultures stimulated with serum or platelet-derived factors was not due to differences in molecular size or extent of sulfation of the proteoglycan molecules.

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30

Theilmeier, Gregor, Carine Michiels, Erik Spaepen, Ingrid Vreys, Désiré Collen, Jos Vermylen e Marc F. Hoylaerts. "Endothelial von Willebrand factor recruits platelets to atherosclerosis-prone sites in response to hypercholesterolemia". Blood 99, n. 12 (15 giugno 2002): 4486–93. http://dx.doi.org/10.1182/blood.v99.12.4486.

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Platelets are thought to play a causal role during atherogenesis. Platelet-endothelial interactions in vivo and their molecular mechanisms under shear are, however, incompletely characterized. Here, an in vivo platelet homing assay was used in hypercholesterolemic rabbits to track platelet adhesion to plaque predilection sites. The role of platelet versus aortic endothelial cell (EC) activation was studied in an ex vivo flow chamber. Pathways of human platelet immobilization were detailed during in vitro perfusion studies. In rabbits, a 0.125% cholesterol diet induced no lesions within 3 months, but fatty streaks were found after 12 months. ECs at segmental arteries of 3- month rabbits expressed more von Willebrand factor (VWF) and recruited 5-fold more platelets than controls (P < .05, n = 5 and 4, respectively). The 3-month ostia had an increased likelihood to recruit platelets compared to control ostia (56% versus 18%, P < .0001, n = 89 and 63, respectively). Ex vivo, the adhesion of 3-month platelets to 3-month aortas was 8.4-fold increased compared to control studies (P < .01, n = 7 and 5, respectively). In vitro, endothelial VWF–platelet glycoprotein (GP) Ib and platelet P-selectin– endothelial P-selectin glycoprotein ligand 1 interactions accounted in combination for 83% of translocation and 90% of adhesion (P < .01, n = 4) of activated human platelets to activated human ECs. Platelet tethering was mainly mediated by platelet GPIbα, whereas platelet GPIIb/IIIa contributed 20% to arrest (P < .05). In conclusion, hypercholesterolemia primes platelets for recruitment via VWF, GPIbα, and P-selectin to lesion-prone sites, before lesions are detectable.

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31

Krauel, Krystin, Nikolay Medvedev, Raghavendra Palankar, Andreas Greinacher e Mihaela Delcea. "Micropatterned array to assess the interaction of single platelets with platelet factor 4-heparin-IgG complexes". Thrombosis and Haemostasis 111, n. 05 (2014): 862–72. http://dx.doi.org/10.1160/th13-09-0752.

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Abstract (sommario):

SummaryWe report a strategy to generate by electron beam lithography high fidelity micropatterned arrays to assess the interaction of single platelets with immobilised ligands. As a proof-of-principle we functionalised the microarrays with platelet factor 4 (PF4)-heparin-IgG complexes. We embedded biotinylated water-soluble quantum dots into polyethylene glycol (PEG)-coated micropatterned arrays and functionalised them via streptavidin to bind biotinylated ligands, here biotinylated-PF4/heparin complexes. The integrity of the PF4/heparin-complexes was shown by binding of anti-PF4/heparin antibodies. Ligand density was quantified by immunofluorescence and immunogold antibody labelling. Real-time calcium imaging was employed for read-out of single platelets activated on micropatterned surfaces functionalised with PF4/heparin-IgG complexes. With the smallest micropatterns (0.5x0.5 µm) we show that single platelets become strongly activated by binding to surface-immobilised PF4/heparin-IgG, while on larger micropatterns (10x10 µm), platelet aggregates formed. These findings that HIT antibodies can cause platelet activation on microarrays illustrate how this novel method opens new avenues to study platelet function at single cell level. Generating functionalized microarray surfaces to which highly complex ligands can be bound and quantified has the potential for platelet and other cell function assays integrated into high-throughput microfluidic microdevices.

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32

Cines, Douglas B., Serge V. Yarovoi, Sergei V. Zaitsev, Tatiana Lebedeva, Lubica Rauova, Mortimer Poncz, Gowthami M. Arepally et al. "Polyphosphate/platelet factor 4 complexes can mediate heparin-independent platelet activation in heparin-induced thrombocytopenia". Blood Advances 1, n. 1 (22 novembre 2016): 62–74. http://dx.doi.org/10.1182/bloodadvances.2016000877.

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Abstract (sommario):

Key Points Polyphosphates form antigenic complexes with PF4 that are recognized by HIT antibodies. Polyphosphate/PF4 complexes released by activated platelets can mediate platelet aggregation by HIT antibodies in the absence of heparin or cell-surface chondroitin sulfate.

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33

Baruch, Dominique, Theo Lindhout, Evelyne Dupuy e Jacques P. Caen. "Thrombin-Induced Platelet Factor Va Formation in Patients with a Gray Platelet Syndrome". Thrombosis and Haemostasis 58, n. 02 (1987): 768–71. http://dx.doi.org/10.1055/s-0038-1645967.

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Abstract (sommario):

SummaryThe present study was initiated to establish the functional factor V concentration in platelets of patients with a mild bleeding disorder ascribed to a gray platelet syndrome. This inherited platelet disorder has been characterized by a specific deficiency of alpha-granules and subsequent deficiencies in the alpha-granule proteins. We found that the concentration of plasma factor V was slightly decreased (70% of normal values). In contrast, platelet factor Va formation was severely impaired. Besides a much lower factor V content than in control platelets (10-20% of normal), the dependency of platelet factor Va formation on tlnumbin concentration was altered. Increasing the thrombin concentration 4-lold compared to the concentration that results in maximal factor Va generation from normal platelets did not result in a maximal factor Va formation from gray platelets. When a suspension of washed gray platelets was incubated with a prostacyclin analogue prior to the stimulation with thrombin, a 10-fold lower factor VQ activity was measured. Thus, thrombin-induced factor Va formation in a suspension of gray platelets is the result of a release reaction, followed by the thrombin-catalyzed activation of released factor V. Whereas the kinetics of the former reaction are apparently impaired, the kinetics of the latter one were found to be identical to those observed for normal platelet and plasma factor V activation.

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34

&NA;. "Platelet factor-4 reverses effects of heparin". Inpharma Weekly &NA;, n. 1064 (novembre 1996): 12. http://dx.doi.org/10.2165/00128413-199610640-00027.

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35

&NA;. "Platelet factor-4 reverses heparin-induced anticoagulation". Inpharma Weekly &NA;, n. 989 (giugno 1995): 11. http://dx.doi.org/10.2165/00128413-199509890-00022.

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36

Mixon, Timothy, e Gregory Dehmer. "Recombinant Platelet Factor 4 for Heparin Neutralization". Seminars in Thrombosis and Hemostasis 30, n. 03 (29 luglio 2004): 369–77. http://dx.doi.org/10.1055/s-2004-831050.

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37

Bikfalvi, Andreas. "Platelet Factor 4: An Inhibitor of Angiogenesis". Seminars in Thrombosis and Hemostasis 30, n. 03 (29 luglio 2004): 379–85. http://dx.doi.org/10.1055/s-2004-831051.

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38

EIKA, C., e H. C. GODAL. "Inactivation of Platelet Factor 4 in Plasma". Scandinavian Journal of Haematology 9, n. 1-6 (24 aprile 2009): 343–50. http://dx.doi.org/10.1111/j.1600-0609.1972.tb00951.x.

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39

Williams, R. D., T. E. Maione, K. E. Lynch, D. F. Keene e M. N. DʼAmbra. "RECOMBINANT HUMAN PLATELET FACTOR 4 (r-PF4)". Anesthesiology 77, Supplement (settembre 1992): A158. http://dx.doi.org/10.1097/00000542-199209001-00158.

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40

Carr, Marcus E., Gilbert C. White e Don A. Gabriel. "Platelet factor 4 enhances fibrin fiber polymerization". Thrombosis Research 45, n. 5 (marzo 1987): 539–43. http://dx.doi.org/10.1016/0049-3848(87)90316-1.

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41

Briquet-Laugier, V., C. Lavenu-Bombled, A. Schmitt, M. Leboeuf, G. Uzan, A. Dubart-Kupperschmitt e J. P. Rosa. "Probing platelet factor 4 alpha-granule targeting". Journal of Thrombosis and Haemostasis 2, n. 12 (dicembre 2004): 2231–40. http://dx.doi.org/10.1111/j.1538-7836.2004.01037.x.

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42

Thachil, Jecko. "The prothrombotic potential of platelet factor 4". European Journal of Internal Medicine 21, n. 2 (aprile 2010): 79–83. http://dx.doi.org/10.1016/j.ejim.2009.11.007.

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43

Smith, C. C. T., L. D. Curtis, A. P. Delamothe, B. N. C. Prichard e D. J. Betteridge. "The Distribution of Catecholamines between Platelets and Plasma in Normal Human Subjects". Clinical Science 69, n. 1 (1 luglio 1985): 1–6. http://dx.doi.org/10.1042/cs0690001.

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Abstract (sommario):

1. We have used high-performance liquid chromatography with electrochemical detection to measure content of adrenaline and noradrenaline in platelets in 13 normal subjects at rest. 2. Subjects were exercised to raise plasma catecholamine levels and promote the platelet release reaction. 3. There was a significant positive correlation between plasma noradrenaline concentrations and platelet noradrenaline content. 4. Platelet/plasma concentration ratios were 1855 for noradrenaline and 268 for adrenaline at rest and 473 and 152 respectively after exercise. 5. Plasma noradrenaline levels positively correlated with age. 6. Determination of platelet factors released to the plasma showed increases of β-thromboglobulin and platelet factor 4 with exercise, whereas thromboxane B2 remained unchanged. No change in platelet catecholamine levels occurred with exercise and no correlations were observed between platelet catecholamines and released platelet factors. 7. These data suggest that plasma catecholamine levels influence platelet content and that noradrenaline and adrenaline are concentrated in platelets.

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44

Shigeta, Osamu, Weiqi Lu, John C. Holt, L. Henry Edmunds e Stefan Niewiarowski. "Ovine platelet factor 4: Purification, amino acid sequence, radioimmunoassay and comparison with platelet factor 4 of other species". Thrombosis Research 64, n. 4 (novembre 1991): 509–20. http://dx.doi.org/10.1016/0049-3848(91)90351-v.

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45

Burgers, JA, RC Schweizer, L. Koenderman, PL Bruijnzeel e JW Akkerman. "Human platelets secrete chemotactic activity for eosinophils". Blood 81, n. 1 (1 gennaio 1993): 49–55. http://dx.doi.org/10.1182/blood.v81.1.49.49.

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Abstract (sommario):

Abstract Thrombin-stimulated platelets liberate factors that induce chemotaxis of eosinophils and raise their cytosolic Ca2+ content ([Ca2+]i). The sources of this activity are the dense- and alpha-granules because inhibition of prostaglandin endoperoxide/thromboxane A2 formation and the platelet-activating factor receptor-antagonist WEB 2086 have no effect. Platelets from patients with Storage-Pool Deficiency show about 60% of the normal chemotactic activity with little effect on [Ca2+]i, whereas completely degranulated platelets fail to affect eosinophils. In concentrations secreted by the platelets, adenosine diphosphate (ADP), and platelet factor 4 have no effect, whereas adenosine triphosphate (ATP) induces a strong chemotactic response and increases [Ca2+]i. However, apart from ATP other modulating factors must be involved as platelet releasates induce more chemotaxis than ATP alone. Thus, platelets secrete factors that activate eosinophils and may contribute to inflammatory and allergic processes.

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46

Burgers, JA, RC Schweizer, L. Koenderman, PL Bruijnzeel e JW Akkerman. "Human platelets secrete chemotactic activity for eosinophils". Blood 81, n. 1 (1 gennaio 1993): 49–55. http://dx.doi.org/10.1182/blood.v81.1.49.bloodjournal81149.

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Abstract (sommario):

Thrombin-stimulated platelets liberate factors that induce chemotaxis of eosinophils and raise their cytosolic Ca2+ content ([Ca2+]i). The sources of this activity are the dense- and alpha-granules because inhibition of prostaglandin endoperoxide/thromboxane A2 formation and the platelet-activating factor receptor-antagonist WEB 2086 have no effect. Platelets from patients with Storage-Pool Deficiency show about 60% of the normal chemotactic activity with little effect on [Ca2+]i, whereas completely degranulated platelets fail to affect eosinophils. In concentrations secreted by the platelets, adenosine diphosphate (ADP), and platelet factor 4 have no effect, whereas adenosine triphosphate (ATP) induces a strong chemotactic response and increases [Ca2+]i. However, apart from ATP other modulating factors must be involved as platelet releasates induce more chemotaxis than ATP alone. Thus, platelets secrete factors that activate eosinophils and may contribute to inflammatory and allergic processes.

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47

Pitsilos, Stephanie, Jennifer Hunt, Emile Mohler, Anand Prabhakar, Mortimer Poncz, Jennine Dawicki, Tigran Khalapyan et al. "Platelet factor 4 localization in carotid atherosclerotic plaques: correlation with clinical parameters". Thrombosis and Haemostasis 90, n. 12 (2003): 1112–20. http://dx.doi.org/10.1160/th03-02-0069.

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Abstract (sommario):

SummaryEmerging evidence supports a role for platelets in the progression of atherosclerosis in addition to an involvement in thrombotic vascular occlusion. Platelet Factor 4 (PF4), a chemokine released by activated platelets, stimulates several pro-atherogenic processes. Therefore, we examined the localization of PF4 and the homologous protein, Neutrophil Activating Protein-2 (NAP-2) in lesions representing the evolution of human atherosclerotic plaques. Carotid plaques from 132 patients with critical carotid stenosis and 6 autopsy specimens were studied. Clinical, histologic and immunohistochemical data were analyzed using a χ2-test. PF4 was detected in the cytoplasm of luminal and neovascular endothelium, in macrophages and in regions of plaque calcification. The presence of PF4 in macrophages and neovascular endothelium correlated with lesion grade (p = 0.004; p = 0.044). Staining of macrophages for PF4 correlated with the presence of symptomatic atherosclerotic disease (p = 0.028). In early lesions, PF4 was commonly found in macrophages of early lesions (Grade I/II), whereas NAP-2 was rarely present.In conclusion, correlation between PF4 deposition, lesion severity and symptomatic atherosclerosis suggests that persistent platelet activation may contribute to the evolution of athero-sclerotic vascular lesions. These studies support the rationale for the chronic use of anti-platelet therapy in patients at risk for developing symptomatic atherosclerosis.

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48

Kelton, JG, JW Smith, TE Warkentin, CP Hayward, GA Denomme e P. Horsewood. "Immunoglobulin G from patients with heparin-induced thrombocytopenia binds to a complex of heparin and platelet factor 4". Blood 83, n. 11 (1 giugno 1994): 3232–39. http://dx.doi.org/10.1182/blood.v83.11.3232.3232.

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Abstract (sommario):

Abstract Heparin-induced thrombocytopenia (HIT) is an important complication of heparin therapy. Although there is general agreement that platelet activation in vitro by the HIT IgG is mediated by the platelet Fc receptor, the interaction among the antibody, heparin, and platelet membrane components is uncertain and debated. In this report, we describe studies designed to address these interactions. We found, as others have noted, that a variety of other sulfated polysaccharides could substitute for heparin in the reaction. Using polysaccharides selected for both size and charge, we found that reactivity depended on two independent factors: a certain minimum degree of sulfation per saccharide unit and a certain minimum size. Hence, highly sulfated but small (< 1,000 daltons) polysaccharides were not reactive nor were large but poorly sulfated polysaccharides. The ability of HIT IgG to recognize heparin by itself was tested by Ouchterlony gel diffusion, ammonium sulfate and polyethylene glycol precipitation, and equilibrium dialysis. No technique demonstrated reactivity. However, when platelet releasate was added to heparin and HIT IgG, a 50-fold increase in binding of radio-labeled heparin to HIT IgG was observed. The releasate was then depleted of proteins capable of binding to heparin by immunoaffinity chromatography. Only platelet factor 4-immunodepleted releasate lost its reactivity with HIT IgG and heparin. Finally, to determine whether the reaction occurred on the surface of platelets or in the fluid phase, washed platelets were incubated with HIT IgG or heparin and after a wash step, heparin or HIT IgG was added, respectively. Reactivity was only noted when platelets were preincubated with heparin. Consistent with these observations was the demonstration of the presence of PF4 on platelets using flow cytometry. These studies indicate that heparin and other large, highly sulfated polysaccharides bind to PF4 to form a reactive antigen on the platelet surface. HIT IgG then binds to this complex with activation of platelets through the platelet Fc receptors.

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49

Kelton, JG, JW Smith, TE Warkentin, CP Hayward, GA Denomme e P. Horsewood. "Immunoglobulin G from patients with heparin-induced thrombocytopenia binds to a complex of heparin and platelet factor 4". Blood 83, n. 11 (1 giugno 1994): 3232–39. http://dx.doi.org/10.1182/blood.v83.11.3232.bloodjournal83113232.

Testo completo

Abstract (sommario):

Heparin-induced thrombocytopenia (HIT) is an important complication of heparin therapy. Although there is general agreement that platelet activation in vitro by the HIT IgG is mediated by the platelet Fc receptor, the interaction among the antibody, heparin, and platelet membrane components is uncertain and debated. In this report, we describe studies designed to address these interactions. We found, as others have noted, that a variety of other sulfated polysaccharides could substitute for heparin in the reaction. Using polysaccharides selected for both size and charge, we found that reactivity depended on two independent factors: a certain minimum degree of sulfation per saccharide unit and a certain minimum size. Hence, highly sulfated but small (< 1,000 daltons) polysaccharides were not reactive nor were large but poorly sulfated polysaccharides. The ability of HIT IgG to recognize heparin by itself was tested by Ouchterlony gel diffusion, ammonium sulfate and polyethylene glycol precipitation, and equilibrium dialysis. No technique demonstrated reactivity. However, when platelet releasate was added to heparin and HIT IgG, a 50-fold increase in binding of radio-labeled heparin to HIT IgG was observed. The releasate was then depleted of proteins capable of binding to heparin by immunoaffinity chromatography. Only platelet factor 4-immunodepleted releasate lost its reactivity with HIT IgG and heparin. Finally, to determine whether the reaction occurred on the surface of platelets or in the fluid phase, washed platelets were incubated with HIT IgG or heparin and after a wash step, heparin or HIT IgG was added, respectively. Reactivity was only noted when platelets were preincubated with heparin. Consistent with these observations was the demonstration of the presence of PF4 on platelets using flow cytometry. These studies indicate that heparin and other large, highly sulfated polysaccharides bind to PF4 to form a reactive antigen on the platelet surface. HIT IgG then binds to this complex with activation of platelets through the platelet Fc receptors.

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50

Duckers, Connie, Paolo Simioni, Luca Spiezia, Claudia Radu, Paolo Dabrilli, Sabrina Gavasso, Jan Rosing e Elisabetta Castoldi. "Residual platelet factor V ensures thrombin generation in patients with severe congenital factor V deficiency and mild bleeding symptoms". Blood 115, n. 4 (28 gennaio 2010): 879–86. http://dx.doi.org/10.1182/blood-2009-08-237719.

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Abstract (sommario):

Abstract Coagulation factor V (FV), present in plasma and platelets, is indispensable to thrombin formation, yet patients with undetectable plasma FV seldom experience major bleeding. We used thrombin generation assays to explore the role of platelet FV in 4 patients with severe congenital FV deficiency (3 with plasma FV clotting activity [FV:C] < 1%). When triggered with tissue factor (TF) concentrations up to 50pM, platelet-poor plasma (PPP) from the patients with undetectable plasma FV showed no thrombin generation, whereas platelet-rich plasma (PRP) formed thrombin already at 1 to 5pM of TF. Thrombin generation in PRP from the FV-deficient patients was enhanced to near-normal levels by platelet activators (collagen or Ca2+-ionophore) and could be completely suppressed by specific FV inhibitors, suggesting FV dependence. Accordingly, platelet FV antigen and activity were measurable in all FV-deficient patients and platelet FVa could be visualized by Western blotting. Normalization of the tissue factor pathway inhibitor (TFPI) level, which is physiologically low in FV-deficient plasma, almost completely abolished thrombin generation in PRP from the FV-deficient patients. In conclusion, patients with undetectable plasma FV may contain functional FV in their platelets. In combination with low TFPI level, residual platelet FV allows sufficient thrombin generation to rescue these patients from fatal bleeding.

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