The Experts below are selected from a list of 1944 Experts worldwide ranked by ideXlab platform

Jawed Fareed - One of the best experts on this subject based on the ideXlab platform.

  • Studies on the thrombogenic effects of recombinant tissue factor. In vivo versus ex vivo findings.
    Seminars in thrombosis and hemostasis, 1995
    Co-Authors: Demetra Callas, Peter Bacher, Jawed Fareed
    Abstract:

    An exposure of Blood to tissue factor (TF) activates the coagulation system by the extrinsic pathway and may cause clot formation. Recombinant TF (r-TF) has been produced and subsequently reconstituted into phospholipid vesicles. The aim of these studies was to elucidate the in vitro procoagulant effects and the in vivo thrombogenicity of r-TF using a rabbit jugular vein stasis thrombosis model. The in vitro studies exhibited a clear concentration-dependent decrease in the Clotting time when rabbit brain thromboplastin was replaced by r-TF in the prothrombin time assay. The in vivo studies revealed a dose-dependent thrombogenicity between 1.6 ng/kg and 50 ng/kg. Electron microscope scanning of the surface of representative clots revealed fibrin-rich structures of heterogeneous density. In comparison, thrombi obtained when FEIBA was utilized as the thrombogenic agent were more homogeneous. The injection of r-TF caused a slight transient drop in Blood pressure with little or no effects on the pulse rate, complete Blood count (CBC) profile, Clotting and amidolytic assays when compared to sham control animals. In contrast, the whole Blood Clotting Parameters (activated Clotting time and thrombelastograph) were prolonged dose-dependently after r-TF injection. The antithrombotic activity of heparin was assessed in this model and compared to the antithrombotic activity when FEIBA is used as the thrombogenic agent. The apparent ED50 of heparin was found to be 4 times higher in the r-TF system. In control studies, no thrombogenic effects were observed by the phospholipid vesicles alone nor by r-TF not embedded in phospholipid vesicles. These data demonstrate that lipidated r-TF is a potent thrombogenic challenge that activates the hemostatic system by the extrinsic pathway.

Vaiva Lesauskaite - One of the best experts on this subject based on the ideXlab platform.

  • A novel ultrasonic method for evaluation of Blood Clotting Parameters
    Journal of Medical Ultrasonics, 2018
    Co-Authors: Vacis Tatarunas, Algirdas Voleisis, Reimondas Sliteris, Liudas Mazeika, Rymantas Kažys, Vaiva Lesauskaite
    Abstract:

    Purpose For long time, Blood clot retraction was measured only by thromboelastographic or platelet contractile force measurement techniques. The purpose of the present study was development of a novel ultrasonic method based on simultaneous monitoring of variations in the ultrasound velocity and the frequency spectrum of the signal propagating in Clotting Blood and its application for automatic evaluation of Blood Clotting Parameters. Methods Simultaneous measurement of ultrasound velocity and variations in the frequency spectrum of wideband ultrasonic signals in Clotting Blood samples was performed. All measurements were performed in pulse-echo mode. Standard clinical data were obtained using routine clinical laboratory methods. Results The amplitudes of ultrasonic signals during native Blood coagulation varied up to ten times for different frequencies. The measurement results of the start and duration of Blood clot retraction differed between patient samples: different components of the Blood coagulation system had significant impact on the Blood clot retraction process. Conclusions Our results showed that during Blood Clotting, the ultrasound velocity and variations in frequency spectrum should be used simultaneously to determine the beginning and duration of Blood clot retraction. Our results also showed that Blood clot retraction is controlled by the activity of factor XIII.

  • A novel ultrasonic method for evaluation of Blood Clotting Parameters
    Journal of Medical Ultrasonics, 2018
    Co-Authors: Vacis Tatarunas, Algirdas Voleisis, Reimondas Sliteris, Liudas Mazeika, Rymantas Kažys, Vaiva Lesauskaite
    Abstract:

    Purpose For long time, Blood clot retraction was measured only by thromboelastographic or platelet contractile force measurement techniques. The purpose of the present study was development of a novel ultrasonic method based on simultaneous monitoring of variations in the ultrasound velocity and the frequency spectrum of the signal propagating in Clotting Blood and its application for automatic evaluation of Blood Clotting Parameters.

  • A novel ultrasonic method for evaluation of Blood Clotting Parameters
    Journal of medical ultrasonics (2001), 2018
    Co-Authors: Vacis Tatarunas, Algirdas Voleisis, Reimondas Sliteris, Liudas Mazeika, Rymantas Kažys, Vaiva Lesauskaite
    Abstract:

    For long time, Blood clot retraction was measured only by thromboelastographic or platelet contractile force measurement techniques. The purpose of the present study was development of a novel ultrasonic method based on simultaneous monitoring of variations in the ultrasound velocity and the frequency spectrum of the signal propagating in Clotting Blood and its application for automatic evaluation of Blood Clotting Parameters. Simultaneous measurement of ultrasound velocity and variations in the frequency spectrum of wideband ultrasonic signals in Clotting Blood samples was performed. All measurements were performed in pulse-echo mode. Standard clinical data were obtained using routine clinical laboratory methods. The amplitudes of ultrasonic signals during native Blood coagulation varied up to ten times for different frequencies. The measurement results of the start and duration of Blood clot retraction differed between patient samples: different components of the Blood coagulation system had significant impact on the Blood clot retraction process. Our results showed that during Blood Clotting, the ultrasound velocity and variations in frequency spectrum should be used simultaneously to determine the beginning and duration of Blood clot retraction. Our results also showed that Blood clot retraction is controlled by the activity of factor XIII.

Demetra Callas - One of the best experts on this subject based on the ideXlab platform.

  • Studies on the thrombogenic effects of recombinant tissue factor. In vivo versus ex vivo findings.
    Seminars in thrombosis and hemostasis, 1995
    Co-Authors: Demetra Callas, Peter Bacher, Jawed Fareed
    Abstract:

    An exposure of Blood to tissue factor (TF) activates the coagulation system by the extrinsic pathway and may cause clot formation. Recombinant TF (r-TF) has been produced and subsequently reconstituted into phospholipid vesicles. The aim of these studies was to elucidate the in vitro procoagulant effects and the in vivo thrombogenicity of r-TF using a rabbit jugular vein stasis thrombosis model. The in vitro studies exhibited a clear concentration-dependent decrease in the Clotting time when rabbit brain thromboplastin was replaced by r-TF in the prothrombin time assay. The in vivo studies revealed a dose-dependent thrombogenicity between 1.6 ng/kg and 50 ng/kg. Electron microscope scanning of the surface of representative clots revealed fibrin-rich structures of heterogeneous density. In comparison, thrombi obtained when FEIBA was utilized as the thrombogenic agent were more homogeneous. The injection of r-TF caused a slight transient drop in Blood pressure with little or no effects on the pulse rate, complete Blood count (CBC) profile, Clotting and amidolytic assays when compared to sham control animals. In contrast, the whole Blood Clotting Parameters (activated Clotting time and thrombelastograph) were prolonged dose-dependently after r-TF injection. The antithrombotic activity of heparin was assessed in this model and compared to the antithrombotic activity when FEIBA is used as the thrombogenic agent. The apparent ED50 of heparin was found to be 4 times higher in the r-TF system. In control studies, no thrombogenic effects were observed by the phospholipid vesicles alone nor by r-TF not embedded in phospholipid vesicles. These data demonstrate that lipidated r-TF is a potent thrombogenic challenge that activates the hemostatic system by the extrinsic pathway.

Vacis Tatarunas - One of the best experts on this subject based on the ideXlab platform.

  • A novel ultrasonic method for evaluation of Blood Clotting Parameters
    Journal of Medical Ultrasonics, 2018
    Co-Authors: Vacis Tatarunas, Algirdas Voleisis, Reimondas Sliteris, Liudas Mazeika, Rymantas Kažys, Vaiva Lesauskaite
    Abstract:

    Purpose For long time, Blood clot retraction was measured only by thromboelastographic or platelet contractile force measurement techniques. The purpose of the present study was development of a novel ultrasonic method based on simultaneous monitoring of variations in the ultrasound velocity and the frequency spectrum of the signal propagating in Clotting Blood and its application for automatic evaluation of Blood Clotting Parameters. Methods Simultaneous measurement of ultrasound velocity and variations in the frequency spectrum of wideband ultrasonic signals in Clotting Blood samples was performed. All measurements were performed in pulse-echo mode. Standard clinical data were obtained using routine clinical laboratory methods. Results The amplitudes of ultrasonic signals during native Blood coagulation varied up to ten times for different frequencies. The measurement results of the start and duration of Blood clot retraction differed between patient samples: different components of the Blood coagulation system had significant impact on the Blood clot retraction process. Conclusions Our results showed that during Blood Clotting, the ultrasound velocity and variations in frequency spectrum should be used simultaneously to determine the beginning and duration of Blood clot retraction. Our results also showed that Blood clot retraction is controlled by the activity of factor XIII.

  • A novel ultrasonic method for evaluation of Blood Clotting Parameters
    Journal of Medical Ultrasonics, 2018
    Co-Authors: Vacis Tatarunas, Algirdas Voleisis, Reimondas Sliteris, Liudas Mazeika, Rymantas Kažys, Vaiva Lesauskaite
    Abstract:

    Purpose For long time, Blood clot retraction was measured only by thromboelastographic or platelet contractile force measurement techniques. The purpose of the present study was development of a novel ultrasonic method based on simultaneous monitoring of variations in the ultrasound velocity and the frequency spectrum of the signal propagating in Clotting Blood and its application for automatic evaluation of Blood Clotting Parameters.

  • A novel ultrasonic method for evaluation of Blood Clotting Parameters
    Journal of medical ultrasonics (2001), 2018
    Co-Authors: Vacis Tatarunas, Algirdas Voleisis, Reimondas Sliteris, Liudas Mazeika, Rymantas Kažys, Vaiva Lesauskaite
    Abstract:

    For long time, Blood clot retraction was measured only by thromboelastographic or platelet contractile force measurement techniques. The purpose of the present study was development of a novel ultrasonic method based on simultaneous monitoring of variations in the ultrasound velocity and the frequency spectrum of the signal propagating in Clotting Blood and its application for automatic evaluation of Blood Clotting Parameters. Simultaneous measurement of ultrasound velocity and variations in the frequency spectrum of wideband ultrasonic signals in Clotting Blood samples was performed. All measurements were performed in pulse-echo mode. Standard clinical data were obtained using routine clinical laboratory methods. The amplitudes of ultrasonic signals during native Blood coagulation varied up to ten times for different frequencies. The measurement results of the start and duration of Blood clot retraction differed between patient samples: different components of the Blood coagulation system had significant impact on the Blood clot retraction process. Our results showed that during Blood Clotting, the ultrasound velocity and variations in frequency spectrum should be used simultaneously to determine the beginning and duration of Blood clot retraction. Our results also showed that Blood clot retraction is controlled by the activity of factor XIII.

Peter Bacher - One of the best experts on this subject based on the ideXlab platform.

  • Studies on the thrombogenic effects of recombinant tissue factor. In vivo versus ex vivo findings.
    Seminars in thrombosis and hemostasis, 1995
    Co-Authors: Demetra Callas, Peter Bacher, Jawed Fareed
    Abstract:

    An exposure of Blood to tissue factor (TF) activates the coagulation system by the extrinsic pathway and may cause clot formation. Recombinant TF (r-TF) has been produced and subsequently reconstituted into phospholipid vesicles. The aim of these studies was to elucidate the in vitro procoagulant effects and the in vivo thrombogenicity of r-TF using a rabbit jugular vein stasis thrombosis model. The in vitro studies exhibited a clear concentration-dependent decrease in the Clotting time when rabbit brain thromboplastin was replaced by r-TF in the prothrombin time assay. The in vivo studies revealed a dose-dependent thrombogenicity between 1.6 ng/kg and 50 ng/kg. Electron microscope scanning of the surface of representative clots revealed fibrin-rich structures of heterogeneous density. In comparison, thrombi obtained when FEIBA was utilized as the thrombogenic agent were more homogeneous. The injection of r-TF caused a slight transient drop in Blood pressure with little or no effects on the pulse rate, complete Blood count (CBC) profile, Clotting and amidolytic assays when compared to sham control animals. In contrast, the whole Blood Clotting Parameters (activated Clotting time and thrombelastograph) were prolonged dose-dependently after r-TF injection. The antithrombotic activity of heparin was assessed in this model and compared to the antithrombotic activity when FEIBA is used as the thrombogenic agent. The apparent ED50 of heparin was found to be 4 times higher in the r-TF system. In control studies, no thrombogenic effects were observed by the phospholipid vesicles alone nor by r-TF not embedded in phospholipid vesicles. These data demonstrate that lipidated r-TF is a potent thrombogenic challenge that activates the hemostatic system by the extrinsic pathway.