The Experts below are selected from a list of 219 Experts worldwide ranked by ideXlab platform
Yona Nadir - One of the best experts on this subject based on the ideXlab platform.
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Heparanase level and Procoagulant Activity are reduced in severe sepsis
European Journal of Haematology, 2017Co-Authors: Moshe Matan, Benjamin Brenner, Daniel King, Eli Peled, Shanny Ackerman, Yaron Bar-lavi, Yona NadirAbstract:BACKGROUND: During severe sepsis, levels and Activity of all coagulation proteins are reduced. Heparanase is implicated in angiogenesis and tumor progression. We previously demonstrated that heparanase also affected the hemostatic system. It forms a complex and increases the Activity of the blood coagulation initiator tissue factor. AIM: To evaluate heparanase levels and Procoagulant Activity as predictors of sepsis severity. MATERIALS AND METHODS: Twenty-one patients with non-trauma, non-surgical sepsis admitted to the intensive care unit and 35 controls were recruited. Plasma samples were drawn from the study participants on days 1 and 7 following admission. RESULTS: Heparanase levels and Procoagulant Activity on day 1 were significantly reduced in patients compared to controls (P
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jak 2 v617f mutation increases heparanase Procoagulant Activity
Thrombosis and Haemostasis, 2015Co-Authors: Inna Kogan, Benjamin Brenner, Elena Axelman, Dafna Chap, Ron Hoffman, Yona NadirAbstract:Patients with polycythaemia vera (PV), essential thrombocythaemia (ET) and primary myelofibrosis (PMF) are at increased risk of arterial and venous thrombosis. In patients with ET a positive correlation was observed between JAK-2 V617F mutation, that facilitates erythropoietin receptor signalling, and thrombotic events, although the mechanism involved is not clear. We previously demonstrated that heparanase protein forms a complex and enhances the Activity of the blood coagulation initiator tissue factor (TF) which leads to increased factor Xa production and subsequent activation of the coagulation system. The present study was aimed to evaluate heparanase Procoagulant Activity in myeloproliferative neoplasms. Forty bone marrow biopsies of patients with ET, PV, PMF and chronic myelogenous leukaemia (CML) were immunostained to heparanase, TF and TF pathway inhibitor (TFPI). Erythropoietin receptor positive cell lines U87 human glioma and MCF-7 human breast carcinoma were studied. Heparanase and TFPI staining were more prominent in ET, PV and PMF compared to CML. The strongest staining was in JAK-2 positive ET biopsies. Heparanase level and Procoagulant Activity were higher in U87 cells transfected to over express JAK-2 V617F mutation compared to control and the effect was reversed using JAK-2 inhibitors (Ruxolitinib, VZ3) and hydroxyurea, although the latter drug did not inhibit JAK-2 phosphorylation. Erythropoietin increased while JAK-2 inhibitors decreased the heparanase level and Procoagulant Activity in U87 and MCF-7 parental cells. In conclusion, JAK-2 is involved in heparanase up-regulation via the erythropoietin receptor. The present findings may potentially point to a new mechanism of thrombosis in JAK-2 positive ET patients.
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heparanase Procoagulant Activity is elevated and predicts survival in non small cell lung cancer patients
Thrombosis Research, 2014Co-Authors: Yona Nadir, Itay Shafat, Galit Sarig, E Axelman, A Meir, M Wollner, R Hoffman, Barry M Brenner, Israel Vlodavsky, N HaimAbstract:Abstract Background Heparanase is implicated in angiogenesis and tumor progression. We had earlier demonstrated that heparanase may also affect the hemostatic system in a non-enzymatic manner. It forms a complex and enhances the Activity of the blood coagulation initiator- tissue factor (TF). Although increased heparanase antigen level in the plasma and biopsies of cancer patients was previously demonstrated, in the present study we evaluated, for the first time, the heparanase Procoagulant Activity in the plasma of patients with lung cancer. Materials and Methods Sixty five patients with non-small cell lung cancer at presentation and twenty controls were recruited. Plasma was studied for TF / heparanase Procoagulant Activity, TF Activity and heparanase Procoagulant Activity using chromogenic assay and heparanase antigen levels by ELISA. Results Heparanase antigen levels were higher in the study group compared to control (P = 0.05). TF / heparanase Activity, and even more apparent, heparanase Procoagulant Activity were significantly higher in the study group compared to controls (P = 0.008, P Conclusions Elevated heparanase Procoagulant Activity in patients with lung cancer reveals a new mechanism of coagulation system activation in malignancy. Heparanase Procoagulant Activity can potentially be used as a predictor for survival.
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heparanase Procoagulant Activity is elevated in women using oral contraceptives
Human Reproduction, 2013Co-Authors: Moshe Matan, Benjamin Brenner, Elena Axelman, Yona NadirAbstract:STUDY QUESTION: What is the effect of estrogen on heparanase procogulant Activity? SUMMARY ANSWER: Estrogen increases heparanase Procoagulant Activity. WHAT IS KNOWN ALREADY: Estrogen therapy increases the risk of thrombosis and was previously found to up-regulate heparanase expression. Heparanase is involved in angiogenesis and metastasis and has been shown to form a complex with tissue factor (TF) and also shown to enhance the generation of factor Xa. STUDY DESIGN SIZE DURATION: A case-control study. Thirty-four healthy women using oral contraceptives (OC) and 41 women not using hormonal therapy and not pregnant per history were enrolled over a 5-month period at the Rambam Medical Center Haifa Israel. In vitro estrogen receptor-positive (MCF-7) and -negative (MDA-231) cell lines were incubated with estrogen tamoxifen and ICI-182.780 a pure estrogen receptor antagonist. The cell medium was evaluated for TF/heparanase complex Activity TF Activity and heparanase Procoagulant Activity by chromogenic substrate. PARTICIPANTS/MATERIALS SETTING METHODS: Exclusion criteria included age <18 years post-menopausal women concomitant medications other than supplement minerals and vitamins acute or chronic illness. MAIN RESULTS AND THE ROLE OF CHANCE: The study demonstrates increased risk of high heparanase Procoagulant Activity in OC users. When a cutoff level of 0.25 (absorbance 405-490 nm) was set the odds ratio was 131 (P < 0.0001). When all results were studied by quartiles in quartiles 3 and 4 the results were almost exclusively of the OC users (P < 0.0001). In cell cultures estrogen and tamoxifen increased heparanase Procoagulant Activity in the medium of estrogen receptor-positive (MCF-7) cells. LIMITATIONS REASONS FOR CAUTION: The main limitation of the current study is that the two estrogens given to the women and cell cultures ethinyl estradiol (EE) and 17-beta-estradiol (E2) respectively may have different effects on the coagulation system although an increase in heparanase Procoagulant Activity was demonstrated in both of them. Although the sample size of the study group was limited significant differences in the activation of the extrinsic coagulation pathway were demonstrated. WIDER IMPLICATIONS OF THE FINDINGS: The clinical relevance of the heparanase Procoagulant Activity assay as a screening tool in thrombophilia work-up should further be elucidated. STUDY FUNDING/COMPETING INTEREST(S): No external funding was sought for this study. Authors Nadir and Brenner are named in a US Provisional Patent Application No. 29509/WO/12 filed on 18.01.2012. The other authors have no conflict of interest to declare. TRIAL REGISTRATION NUMBER: N/A.
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Heparanase Procoagulant Activity is elevated in women using oral contraceptives
Human Reproduction, 2013Co-Authors: Moshe Matan, Benjamin Brenner, Elena Axelman, Yona NadirAbstract:STUDY QUESTION: What is the effect of estrogen on heparanase procogulant Activity? SUMMARY ANSWER: Estrogen increases heparanase Procoagulant Activity. WHAT IS KNOWN ALREADY: Estrogen therapy increases the risk of thrombosis and was previously found to up-regulate heparanase expression. Heparanase is involved in angiogenesis and metastasis and has been shown to form a complex with tissue factor (TF) and also shown to enhance the generation of factor Xa. STUDY DESIGN SIZE DURATION: A case-control study. Thirty-four healthy women using oral contraceptives (OC) and 41 women not using hormonal therapy and not pregnant per history were enrolled over a 5-month period at the Rambam Medical Center Haifa Israel. In vitro estrogen receptor-positive (MCF-7) and -negative (MDA-231) cell lines were incubated with estrogen tamoxifen and ICI-182.780 a pure estrogen receptor antagonist. The cell medium was evaluated for TF/heparanase complex Activity TF Activity and heparanase Procoagulant Activity by chromogenic substrate. PARTICIPANTS/MATERIALS SETTING METHODS: Exclusion criteria included age
Daniel B Rifkin - One of the best experts on this subject based on the ideXlab platform.
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expression of tissue factor Procoagulant Activity regulation by cytosolic calcium
Proceedings of the National Academy of Sciences of the United States of America, 1990Co-Authors: Ronald Bach, Daniel B RifkinAbstract:Abstract Intact bovine fibroblasts, pericytes, and kidney cells manifested significantly less tissue factor Procoagulant Activity than their disrupted counterparts. Addition of calcium ionophore A23187 rapidly and reversibly enhanced the cell-surface expression of tissue factor in intact cells up to the level achieved by disruption. Inhibitors of calmodulin blocked the ionophore-dependent enhancement of Procoagulant Activity. Similar kinetic parameters were obtained for factor X hydrolysis by tissue factor-factor VIIa on unperturbed pericytes and phosphatidylcholine vesicles. Increase in Vmax and decrease in apparent Km for this reaction were seen after either disruption or ionophore stimulation of the pericytes. Addition of phosphatidylserine to the reconstituted phospholipid vesicles also increased the Vmax and decreased the apparent Km for factor X hydrolysis. These data agree with the hypothesis that the expression of tissue factor Procoagulant Activity on cell surfaces is modulated by calcium-mediated changes in the asymmetric distribution of phosphatidylserine in plasma membrane.
Benjamin Brenner - One of the best experts on this subject based on the ideXlab platform.
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Heparanase level and Procoagulant Activity are reduced in severe sepsis
European Journal of Haematology, 2017Co-Authors: Moshe Matan, Benjamin Brenner, Daniel King, Eli Peled, Shanny Ackerman, Yaron Bar-lavi, Yona NadirAbstract:BACKGROUND: During severe sepsis, levels and Activity of all coagulation proteins are reduced. Heparanase is implicated in angiogenesis and tumor progression. We previously demonstrated that heparanase also affected the hemostatic system. It forms a complex and increases the Activity of the blood coagulation initiator tissue factor. AIM: To evaluate heparanase levels and Procoagulant Activity as predictors of sepsis severity. MATERIALS AND METHODS: Twenty-one patients with non-trauma, non-surgical sepsis admitted to the intensive care unit and 35 controls were recruited. Plasma samples were drawn from the study participants on days 1 and 7 following admission. RESULTS: Heparanase levels and Procoagulant Activity on day 1 were significantly reduced in patients compared to controls (P
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jak 2 v617f mutation increases heparanase Procoagulant Activity
Thrombosis and Haemostasis, 2015Co-Authors: Inna Kogan, Benjamin Brenner, Elena Axelman, Dafna Chap, Ron Hoffman, Yona NadirAbstract:Patients with polycythaemia vera (PV), essential thrombocythaemia (ET) and primary myelofibrosis (PMF) are at increased risk of arterial and venous thrombosis. In patients with ET a positive correlation was observed between JAK-2 V617F mutation, that facilitates erythropoietin receptor signalling, and thrombotic events, although the mechanism involved is not clear. We previously demonstrated that heparanase protein forms a complex and enhances the Activity of the blood coagulation initiator tissue factor (TF) which leads to increased factor Xa production and subsequent activation of the coagulation system. The present study was aimed to evaluate heparanase Procoagulant Activity in myeloproliferative neoplasms. Forty bone marrow biopsies of patients with ET, PV, PMF and chronic myelogenous leukaemia (CML) were immunostained to heparanase, TF and TF pathway inhibitor (TFPI). Erythropoietin receptor positive cell lines U87 human glioma and MCF-7 human breast carcinoma were studied. Heparanase and TFPI staining were more prominent in ET, PV and PMF compared to CML. The strongest staining was in JAK-2 positive ET biopsies. Heparanase level and Procoagulant Activity were higher in U87 cells transfected to over express JAK-2 V617F mutation compared to control and the effect was reversed using JAK-2 inhibitors (Ruxolitinib, VZ3) and hydroxyurea, although the latter drug did not inhibit JAK-2 phosphorylation. Erythropoietin increased while JAK-2 inhibitors decreased the heparanase level and Procoagulant Activity in U87 and MCF-7 parental cells. In conclusion, JAK-2 is involved in heparanase up-regulation via the erythropoietin receptor. The present findings may potentially point to a new mechanism of thrombosis in JAK-2 positive ET patients.
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heparanase Procoagulant Activity is elevated in women using oral contraceptives
Human Reproduction, 2013Co-Authors: Moshe Matan, Benjamin Brenner, Elena Axelman, Yona NadirAbstract:STUDY QUESTION: What is the effect of estrogen on heparanase procogulant Activity? SUMMARY ANSWER: Estrogen increases heparanase Procoagulant Activity. WHAT IS KNOWN ALREADY: Estrogen therapy increases the risk of thrombosis and was previously found to up-regulate heparanase expression. Heparanase is involved in angiogenesis and metastasis and has been shown to form a complex with tissue factor (TF) and also shown to enhance the generation of factor Xa. STUDY DESIGN SIZE DURATION: A case-control study. Thirty-four healthy women using oral contraceptives (OC) and 41 women not using hormonal therapy and not pregnant per history were enrolled over a 5-month period at the Rambam Medical Center Haifa Israel. In vitro estrogen receptor-positive (MCF-7) and -negative (MDA-231) cell lines were incubated with estrogen tamoxifen and ICI-182.780 a pure estrogen receptor antagonist. The cell medium was evaluated for TF/heparanase complex Activity TF Activity and heparanase Procoagulant Activity by chromogenic substrate. PARTICIPANTS/MATERIALS SETTING METHODS: Exclusion criteria included age <18 years post-menopausal women concomitant medications other than supplement minerals and vitamins acute or chronic illness. MAIN RESULTS AND THE ROLE OF CHANCE: The study demonstrates increased risk of high heparanase Procoagulant Activity in OC users. When a cutoff level of 0.25 (absorbance 405-490 nm) was set the odds ratio was 131 (P < 0.0001). When all results were studied by quartiles in quartiles 3 and 4 the results were almost exclusively of the OC users (P < 0.0001). In cell cultures estrogen and tamoxifen increased heparanase Procoagulant Activity in the medium of estrogen receptor-positive (MCF-7) cells. LIMITATIONS REASONS FOR CAUTION: The main limitation of the current study is that the two estrogens given to the women and cell cultures ethinyl estradiol (EE) and 17-beta-estradiol (E2) respectively may have different effects on the coagulation system although an increase in heparanase Procoagulant Activity was demonstrated in both of them. Although the sample size of the study group was limited significant differences in the activation of the extrinsic coagulation pathway were demonstrated. WIDER IMPLICATIONS OF THE FINDINGS: The clinical relevance of the heparanase Procoagulant Activity assay as a screening tool in thrombophilia work-up should further be elucidated. STUDY FUNDING/COMPETING INTEREST(S): No external funding was sought for this study. Authors Nadir and Brenner are named in a US Provisional Patent Application No. 29509/WO/12 filed on 18.01.2012. The other authors have no conflict of interest to declare. TRIAL REGISTRATION NUMBER: N/A.
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Heparanase Procoagulant Activity is elevated in women using oral contraceptives
Human Reproduction, 2013Co-Authors: Moshe Matan, Benjamin Brenner, Elena Axelman, Yona NadirAbstract:STUDY QUESTION: What is the effect of estrogen on heparanase procogulant Activity? SUMMARY ANSWER: Estrogen increases heparanase Procoagulant Activity. WHAT IS KNOWN ALREADY: Estrogen therapy increases the risk of thrombosis and was previously found to up-regulate heparanase expression. Heparanase is involved in angiogenesis and metastasis and has been shown to form a complex with tissue factor (TF) and also shown to enhance the generation of factor Xa. STUDY DESIGN SIZE DURATION: A case-control study. Thirty-four healthy women using oral contraceptives (OC) and 41 women not using hormonal therapy and not pregnant per history were enrolled over a 5-month period at the Rambam Medical Center Haifa Israel. In vitro estrogen receptor-positive (MCF-7) and -negative (MDA-231) cell lines were incubated with estrogen tamoxifen and ICI-182.780 a pure estrogen receptor antagonist. The cell medium was evaluated for TF/heparanase complex Activity TF Activity and heparanase Procoagulant Activity by chromogenic substrate. PARTICIPANTS/MATERIALS SETTING METHODS: Exclusion criteria included age
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an assay to evaluate heparanase Procoagulant Activity
Thrombosis Research, 2011Co-Authors: Yona Nadir, Yael Kenig, Arie Drugan, Itay Shafat, Benjamin BrennerAbstract:BACKGROUND: Heparanase that was cloned from and is abundant in the placenta is implicated in cell invasion, tumor metastasis and angiogenesis. Recently, we demonstrated that heparanase is directly involved in the regulation of the hemostatic system. Heparanase was shown to form a complex and enhance tissue factor (TF) Activity, resulting in increased factor Xa production (Nadir et al. Haematologica, 2010). The present work suggests a novel assay to evaluate heparanase Procoagulant Activity. METHODS: Heparanase Procoagulant Activity was studied using purified proteins of heparanase, TF, factor VIIa and factor X. The assay was verified in 55 plasma samples and compared to heparanase and tissue factor pathway inhibitor (TFPI) levels by ELISA and factor Xa, thrombin levels and antithrombin Activity by chromogenic substrates. Thirty five samples were of third-trimester pregnant women (weeks 36-41) who were in labor or came for appointed elective cesarean section and 20 control samples were of non-pregnant healthy women. RESULTS: Heparanase Procoagulant Activity assay was shown to differentiate heparanase Procoagulant effect from TF Activity, in purified proteins. Heparanase Procoagulant Activity was significantly higher in the plasma of pregnant women compared to non-pregnant (p < 0.005). Heparanase relative contribution to the TF / heparanase complex Activity was significantly higher in the plasma of pregnant women compared to non-pregnant (29% increase, p < 0.0001). Differences in heparanase Procoagulant Activity were more prominent than changes in heparanase levels by ELISA, TF Activity, factor Xa, thrombin and free TFPI levels. CONCLUSIONS: Heparanase Procoagulant Activity can be determined by the suggested assay. The assay revealed a significant contribution of heparanase to the Procoagulant state in late third-trimester pregnancy and at delivery.
David J Schneider - One of the best experts on this subject based on the ideXlab platform.
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platelet white blood cell wbc interaction wbc apoptosis and Procoagulant Activity in stored red blood cells
Transfusion, 2011Co-Authors: Friederike K. Keating, Saulius Butenas, Mark Fung, David J SchneiderAbstract:BACKGROUND: Nonleukoreduced units of red blood cells (RBCs) contain activated platelets (PLTs) that interact with white blood cells (WBCs) and may promote inflammation and thrombosis in the recipient. The aim of this study was to characterize PLT-WBC interactions (PLT-WBC aggregates [PLAs]), WBC apoptosis, WBC death, and the development of Procoagulant Activity in RBCs during storage. STUDY DESIGN AND METHODS: RBCs were prepared from volunteer donor blood and stored. Samples were analyzed with flow cytometry between Days 1 and 15 to measure PLT-monocyte aggregate (PMA) and PLT-neutrophil aggregate (PNA) formation, WBC apoptosis (annexin V binding), and cell death (binding of 7-aminoactinomycin D). Procoagulant Activity in the supernatant of four RBC preparations was assessed between Days 1 and 39 using a clotting assay with and without the addition of an inhibitory anti-tissue factor (TF) antibody, αTF-5. RESULTS: PLA formation was extensive and maximal on Day 3 of storage (PNA, 23 ± 13%; PMA, 93 ± 4%; n = 6). Apoptosis was progressive throughout storage, with 95 ± 4% of neutrophils and 73 ± 19% of monocytes binding annexin V on Day 15. Cell death became measurable after apoptosis. Procoagulant Activity was observed in all RBCs but with varying temporal patterns. It was partially TF dependent and removed with high-speed centrifugation, suggestive of an association with microparticles. CONCLUSION: The activation of PLTs during the storage of RBCs induces PLA formation that precedes WBC apoptosis and death. Procoagulant Activity, likely associated with microparticles derived from apoptotic WBCs, may contribute to adverse effects of stored, nonleukoreduced RBCs.
Jin Zhou - One of the best experts on this subject based on the ideXlab platform.
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Expression and Procoagulant Activity of phosphatidylserine on the normal blood cells
Chinese Journal of Hematology, 2011Co-Authors: Jin Zhou, Yanhua SuAbstract:OBJECTIVE: To investigate the expression and Procoagulant Activity of phosphatidylserine (PS) on the normal peripheral blood cells of adults. METHODS: Normal peripheral blood samples were collected from 10 healthy volunteers (5 ml from each volunteer), platelets, neutrophils, lymphocytes and erythrocytes were isolated. The expression and Procoagulant Activity of PS on normal blood cells were identified by flow cytometry, inhibition test with lactadherin as PS probe and coagulation anticoagulant, respectively. RESULTS: There was PS expression on a few normal blood cells (9.1%, 5.4%, 3.9% and 3.2% in platelets, neutrophils, lymphocytes and erythrocytes, respectively). The PS on these normal blood cells in vitro showed significant Procoagulant Activity. The plasma recalcification time was shortened by 47%, 36.5%, 25% and 12.5% by platelets, neutrophils, lymphocytes and erythrocytes, respectively; the formation of factor Xa (through both intrinsic and extrinsic pathways) and thrombin was also increased by 13% - 26% by platelets, neutrophils, lymphocytes and erythrocytes, respectively. CONCLUSION: The PS on normal blood cells in vivo may play a crucial role in the coagulation cascade.
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Procoagulant Activity and phosphatidylserine of amniotic fluid cells
Thrombosis and Haemostasis, 2009Co-Authors: Jin Zhou, Hongjuan Yu, Chengfang Lu, Gary E GilbertAbstract:Amniotic fluid (AF) may induce disseminated intravascular coagulation (DIC) when it enters maternal circulation by breaching the placental-maternal circulation barrier. The precise mechanism of the Procoagulant Activity of AF is unclear, but tissue factor (TF) has been proposed to be the main cause. As one constituent of AF, AF cells accumulate and undergo apoptosis continuously. Therefore, we speculate that AF cells have Procoagulant Activity due to the externalisation of phosphatidylserine (PS). The present study aims to demonstrate that, in addition to TF, the PS that is externalised on AF cells is important for the Procoagulant Activity of AF. Ten AF samples from parturient women were analysed using lactadherin as the probe for PS. Anti-TF antibody also was used to identify TF and its associated coagulation functions in AF cells. Normal platelets, neutrophils, and lymphocytes were harvested as controls. Confocal microscopy and flow cytometry was used to assess PS expression on AF cells. The Procoagulant Activity of AF cells was demonstrated by a plasma coagulation assay and further confirmed by factor Xase/prothrombinase assays. PS and TF were present on most AF cells, providing substantial Procoagulant Activity. Furthermore, factor Xase and prothrombinase assays showed that AF cells substantially enforced the activation of factor X and prothrombin. PS on AF cells is an important Procoagulant source for AF. Lactadherin is an ideal anticoagulant for inhibiting the Procoagulant Activity of AF cells.
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Procoagulant Activity and phosphatidylserine of amniotic fluid cells
Blood, 2008Co-Authors: Jin Zhou, Hongjuan Yu, Chengfang Lu, Gary E GilbertAbstract:Amniotic fluid (AF) may induce disseminated intravascular coagulation when it enters maternal circulation by breaching the placental-maternal circulation barrier. The precise mechanism of the Procoagulant Activity of AF is unclear, we speculate that AF cells have Procoagulant Activity due to the externalization of phosphatidylserine (PS). The present study aims to demonstrate that, in addition to tissue factor (TF), the PS that is externalized on AF cells is important for the Procoagulant Activity of AF. Ten AF samples from parturient women were analyzed and normal platelets, neutrophils, and lymphocytes were harvested as controls. Lactadherin, a glycoprotein, binds to membranes containing PS, inhibits prothrombinase Activity, factor Xase Activity, and tissue factor-factor VIIa Activity by blocking PS-containing membrane binding. Thus lactadherin was utilized as a PS probe for flow cytometry and confocal microscopy to enable comparison of PS distribution with TF and intrinsic factor Xase complex formation. Procoagulant Activity of AF cells was first measured in plasma with AF cells serving as thromboplastin. Activity of AF cells supporting intrinsic and extrinsic factor Xase complexes was measured in purified systems. Lactadherin, as an agent to block exposed PS, inhibited 85% of intrinsic and extrinsic factor Xase Activity. Competition binding studies indicated that lactadherin competed for 55% of factor VIII binding sites. However, binding of factor VIII was completely inhibited by PS-containing vesicles and by mAb that recognize the factor VIII C2 domain indicating that all fVIII binding was mediated by the membrane-binding motif or an overlapping epitope. Confocal microscopy identified patches and a rim-pattern indicating a diffuse PS exposure. Lactadherin binding sites and TF distributed to discreet, but overlapping regions of the cells. These results indicate that PS exposure parallels Procoagulant Activity on AF cells and is required for at least 85% of intrinsic and extrinsic factor Xase activities. However, the topographical pattern of PS exposure differs from the pattern of TF and the pattern of binding site distribution for intrinsic factor Xase complexes. Thus, the results imply that intrinsic factor Xase and extrinsic factor Xase Activity are localized to small cell regions where PS exposure coincides with TF and intrinsic factor Xase binding sites, respectively.
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Increased Procoagulant Activity of red blood cells in the presence of cisplatin.
Chinese Medical Journal, 2008Co-Authors: Chengfang Lu, Hongjuan Yu, Jin ZhouAbstract:BACKGROUND: Cisplatin based chemotherapy is a well recognized risk factor for coagulation disorders and thrombosis. The pathophysiological mechanisms by which cisplatin promote thrombosis are not well understood. METHODS: Red blood cells (RBCs) were separated from peripheral blood of patients with breast cancer (n = 10) and healthy adults (n = 6) and treated with cisplatin. Coagulation time of RBCs was assessed by one step recalcification time and the productions of thrombin, intrinsic and extrinsic factor Xa were measured in the presence or absence of various concentrations of lactadherin. Exposed phosphatidylserine was stained with lactadherin and observed by confocal microscopy and flow cytometry. RESULTS: Neither fresh RBCs nor RBCs treated without cisplatin had potent Procoagulant Activity. Cisplatin treatment increased Procoagulant Activity of RBCs in a cell number- and concentration-dependent manner. Exposed phosphatidylserine was stained with lactadherin and after cisplatin treatment, strong fluorescence was revealed by confocal microscopy. Lactadherin bound RBCs from patients with breast cancer increased from (1.9 +/- 0.5)% on control RBCs to (68.0 +/- 3.5)% on RBCs treated with 10 micromol/L cisplatin for 24 hours. CONCLUSIONS: Cisplatin treatment increases Procoagulant Activity of RBCs, which have a strong association with exposure of phosphatidylserine. The increased Procoagulant Activity may contribute to the pathogenesis of thrombophilia during cisplatin based chemotherapy in breast cancer patients.