A Collaborative Study to Establish the 2nd International Standard for Tissue Plasminogen Activator (t-PA)

SummaryAn international collaborative study involving ten laboratories located in eight different countries was undertaken in order to replace the current International Standard (I.S.) for tissue plasminogen activator (t-PA). Two lyophilised candidate preparations of high purity were assessed in comparison with the current I.S. for t-PA using only a clot lysis assay. One preparation (coded 861670) was purified from a cultured melanoma cell supernatant and was about 98% single chain t-PA while the other preparation (coded 861624) was derived from Chinese hamster ovary (CHO) cells following DNA recombinant procedures and was 75% single chain t-PA.Both candidate preparations of t-PA compared in quite a satisfactory manner with the current I.S. from the viewpoint of the biometrics of parallel line bioassays and both preparations were quite stable for long periods at low temperatures and stable from up to 1 month at temperatures of 20° and 38° C. Both fultil the criteria to serve as a satisfactory Znd International Standard for t-PA. The Fibrinolysis Subcommittee of the International Committee for Thrombosis and Haemostasis recommended the melanoma source t-PA (861670) as the next I.S. in order to maintain continuity with the 1st I.S. which was also a melanomatype preparation. The data from the ten laboratories indicated that each ampoule of the new proposed standard contains 850 international units of t-PA activity by the clot lysis assay. It is planned to present the results of this study to the Expert Committee on Biological Standardization of the World Health Organization at its next meeting and to request that the preparation of t-PA, coded 861670, be established as the 2ndlnternational Standard for t-PA.

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A Collaborative Study of a Proposed International Standard for Tissue Plasminogen Activator (t-PA)

Thrombosis and Haemostasis ◽

10.1055/s-0038-1661253 ◽

1985 ◽

Vol 53 (01) ◽

pp. 134-136 ◽

Cited By ~ 70

Author(s):

P J Gaffney ◽

A D Curtis

Keyword(s):

Plasminogen Activator ◽

Tissue Plasminogen Activator ◽

Collaborative Study ◽

International Committee ◽

World Health ◽

Clot Lysis ◽

Expert Committee ◽

International Standard ◽

Tissue Plasminogen ◽

Health Organization

SummaryAn international collaborative study involving seven laboratories was undertaken to assess which of three lyophilised preparations might serve as an International Standard (I.S.) for tissue plasminogen activator (t-PA). Two of the preparations were isolates from human melanoma cell cultures while one was of pig heart origin. A clot lysis assay was used by all participants in the study.The data suggested that both preparations of human cell origin were comparable, in that their log dose-response lines were parallel, while that of the porcine preparation was not. Accelerated degradation studies indicated that one melanoma extract (denoted 83/517) was more stable than the other and it was decided to recommend preparation 83/517 as the standard for t-PA. The International Committee for Thrombosis and Haemostasis (Stockholm 1983) has recommended the use of this material as a standard and it has been established by the Expert Committee on Biological Standardization of the World Health Organization as the International, Standard for tissue plasminogen activator, with an assigned potency of 1000 International Units per ampoule.

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A Collaborative Study to Establish a Standard for High Molecular Weight Urinary-Type Plasminogen Activator (HMW/u-PA)

Thrombosis and Haemostasis ◽

10.1055/s-0038-1647326 ◽

1990 ◽

Vol 64 (03) ◽

pp. 398-401 ◽

Cited By ~ 13

Author(s):

P J Gaffney ◽

A B Heath

Keyword(s):

Molecular Weight ◽

High Molecular Weight ◽

Plasminogen Activator ◽

Collaborative Study ◽

World Health ◽

Expert Committee ◽

Single Chain ◽

Code Number ◽

International Standard ◽

Type Plasminogen Activator

SummaryAn international collaborative study involving eleven laboratories located in eight countries was undertaken to establish an International Standard for high molecular weight urinary-type plasminogen activator (HMW/u-PA). The current International Reference Preparation (IRP code numbered 66146) for urinarytype plasminogen activator (u-PA) ot urokinase (see Nomenclature footnote) is a 66/34 molar ratio mixture of low molecular weight (LMW) - and high molecular weight (HMW) - u-PA’s and is considered unsuitable as a standard for homogeneous preparations of HMW/u-PA. The putative standard for HMWu-PA (code number, 87/594) was compared for potency in a clot lysis assay with the current IRP for u-PA (code numbet, 66146) and a lyophilised preparation of single chain urinary-type plasminogen activator (SCuPA), the latter being used in the assay without prior activation by plasmin to its active two chain form (TCuPA).Both the proposed standard for HMWu-PA (871594) and the SCuPA compared in a statistically satisfactory manner in parallel line bioassays with the current IRP for u-PA (66146), thus allowing potency estimates to be obtained for these two materials in relation to defined international units. Data from the eleven laboratories indicated that each ampoule of the proposed standard for HMWu-PA contained 4,300 i. u. of activity and was stable for over 1 year at 4° C. Most participants indicated that SCuPA expressed only a small amount of its activity without a prior activator step and this suggests that SCuPA assays need to be preceded by a plasmin activation stepThe Expert Committee on Biological Standardization of the World Health Organisation (Geneva, Oct 1989) established 871 594 as the International Standard for high molecular weight two chain urinary type plasminogen activator (HMW/TCuPA, of HMWu-PA), with an assigned unitage of 4,300 international units per ampoule.

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A Collaborative Study to Establish the 3rd International Standard for Tissue Plasminogen Activator

Thrombosis and Haemostasis ◽

10.1055/s-0037-1613201 ◽

2002 ◽

Vol 88 (08) ◽

pp. 294-297 ◽

Cited By ~ 11

Author(s):

Dawn Sands ◽

Colin Whitton ◽

R. Merton ◽

Colin Longstaff

Keyword(s):

Plasminogen Activator ◽

Tissue Plasminogen Activator ◽

Collaborative Study ◽

Reference Method ◽

Mean Value ◽

International Standards ◽

International Standard ◽

Tissue Plasminogen ◽

The Mean ◽

Study Participants

SummaryAn international collaborative study was organised to replace the 2nd International Standard (IS) for tissue plasminogen activator (tPA). The 2nd IS for tPA (86/670) was used to calibrate the replacement Standard, which was selected from two candidate materials included in the collaborative study. Participants were provided with five sets of four samples (A, B, C, D) and asked to use sample A (2nd IS, 86/670, 850 IU/ml) to determine the activity of B (86/624, approximately 850 IU/ml), C and D (coded duplicates of the same material, 98/714 approximately 11000 IU/ml). A total of 14 laboratories returned results from Europe, USA, Japan and Australia, providing data from 60 independent assays. Four laboratories used a reference method based on a published monograph from the European Pharmacopoeia for Alteplase for Injection, 1998, and the remaining 10 used their own method. Fibrin was used as promoter of tPA activity by 12 out of the 14 laboratories, the remaining two used kits where fibrinogen fragments were the promoter. Data from this collaborative study and the previous study to establish the 2nd IS for tPA show that tPA from melanoma cells and recombinant tPA from CHO cells are both suitable materials as International Standards. It was agreed that sample C, D, recombinant tPA, 98/714, be established as the 3rd International Standard for tPA with a potency of 10000 IU per ampoule, calculated as the mean value from laboratories using fibrin as a promoter of tPA activity. The standard was established by WHO in November 2000.

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The kinetics of plasminogen activation by thrombin-cleaved pro- urokinase and promotion of its activity by fibrin fragment E-2 and by tissue plasminogen activator

Blood ◽

10.1182/blood.v81.4.980.bloodjournal814980 ◽

1993 ◽

Vol 81 (4) ◽

pp. 980-987

Author(s):

JN Liu ◽

V Gurewich

Keyword(s):

Plasminogen Activator ◽

Tissue Plasminogen Activator ◽

Catalytic Efficiency ◽

Clot Lysis ◽

Plasminogen Activation ◽

Single Chain ◽

Carboxypeptidase B ◽

Thrombin Cleavage ◽

Tissue Plasminogen ◽

A Chain

Thrombin hydrolyzes the Arg156-Phe157 bond in pro-urokinase (pro-UK), two residues from the activation site, generating a two-chain form (thromb-UK) believed to have little activity and that is resistant to plasmin activation. The kinetic constants for thromb-UK against synthetic substrate (S2444) were found to be essentially identical to pro-UK. Against native plasminogen, thromb-UK had a lower Michaelis constant (KM) and a higher (2-fold) catalytic efficiency. However, this difference with pro-UK was nullified by carboxypeptidase B (CpB) treatment of thromb-UK to remove the C-terminal arginine on the A- chain. Plasminogen activation by thromb-UK was substantially promoted by fibrin fragment E-2 but not by other fibrin derivatives, a phenomenon previously observed with pro-UK. Similarly, clot lysis by thromb-UK was promoted by tissue plasminogen activator because their combined effect was synergistic. Fibrinogenolysis in plasma occurred at 80-fold the concentration of thromb-UK as pro-UK, reflecting the 90- fold greater plasmin resistance of thromb-UK. Addition of a CpB inhibitor to the plasma enhanced fibrinogenolysis by thromb-UK and pro- UK by approximately 16%, consistent with the promotion of both forms by certain C-terminal lysines. In conclusion, CpB-thromb-UK corresponds functionally to a plasmin resistant form of pro-UK, indicating that the catalytic site of the single-chain pro-UK is unaffected by thrombin cleavage. The effect of CpB indicates that the C-terminal Arg of thromb- UK slightly enhances its affinity for plasminogen. Thromb-UK has potential plasminogen-activating activity at surfaces where C-terminal lysines, functionally comparable to fragment E-2, are found.

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The kinetics of plasminogen activation by thrombin-cleaved pro- urokinase and promotion of its activity by fibrin fragment E-2 and by tissue plasminogen activator

Blood ◽

10.1182/blood.v81.4.980.980 ◽

1993 ◽

Vol 81 (4) ◽

pp. 980-987 ◽

Cited By ~ 29

Author(s):

JN Liu ◽

V Gurewich

Keyword(s):

Plasminogen Activator ◽

Tissue Plasminogen Activator ◽

Catalytic Efficiency ◽

Clot Lysis ◽

Plasminogen Activation ◽

Single Chain ◽

Carboxypeptidase B ◽

Thrombin Cleavage ◽

Tissue Plasminogen ◽

A Chain

Abstract Thrombin hydrolyzes the Arg156-Phe157 bond in pro-urokinase (pro-UK), two residues from the activation site, generating a two-chain form (thromb-UK) believed to have little activity and that is resistant to plasmin activation. The kinetic constants for thromb-UK against synthetic substrate (S2444) were found to be essentially identical to pro-UK. Against native plasminogen, thromb-UK had a lower Michaelis constant (KM) and a higher (2-fold) catalytic efficiency. However, this difference with pro-UK was nullified by carboxypeptidase B (CpB) treatment of thromb-UK to remove the C-terminal arginine on the A- chain. Plasminogen activation by thromb-UK was substantially promoted by fibrin fragment E-2 but not by other fibrin derivatives, a phenomenon previously observed with pro-UK. Similarly, clot lysis by thromb-UK was promoted by tissue plasminogen activator because their combined effect was synergistic. Fibrinogenolysis in plasma occurred at 80-fold the concentration of thromb-UK as pro-UK, reflecting the 90- fold greater plasmin resistance of thromb-UK. Addition of a CpB inhibitor to the plasma enhanced fibrinogenolysis by thromb-UK and pro- UK by approximately 16%, consistent with the promotion of both forms by certain C-terminal lysines. In conclusion, CpB-thromb-UK corresponds functionally to a plasmin resistant form of pro-UK, indicating that the catalytic site of the single-chain pro-UK is unaffected by thrombin cleavage. The effect of CpB indicates that the C-terminal Arg of thromb- UK slightly enhances its affinity for plasminogen. Thromb-UK has potential plasminogen-activating activity at surfaces where C-terminal lysines, functionally comparable to fragment E-2, are found.

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A Collaborative Study to Establish the Second International Standard for Streptokinase

Thrombosis and Haemostasis ◽

10.1055/s-0038-1647298 ◽

1990 ◽

Vol 64 (02) ◽

pp. 267-269 ◽

Cited By ~ 7

Author(s):

A B Heath ◽

P J Gaffney

Keyword(s):

High Purity ◽

Collaborative Study ◽

World Health Organisation ◽

World Health ◽

Clot Lysis ◽

Current Standard ◽

International Standard ◽

Accelerated Degradation ◽

The World ◽

International Collaborative Study

SummaryAn International Standard for Streptokinase - Streptodomase (62/7) has been used to calibrate high purity clinical batches of SK since 1965. An international collaborative study, involving six laboratories, was undertaken to replace this standard with a high purity standard for SK. Two candidate preparations (88/826 and 88/824) were compared by a clot lysis assay with the current standard (62/7). Potencies of 671 i.u. and 461 i.u. were established for preparations A (88/826) and B (88/824), respectively.Either preparation appeared suitable to serve as a standard for SK. However, each ampoule of preparation A (88/826) contains a more appropriate amount of SK activity for potency testing, and is therefore preferred. Accelerated degradation tests indicate that preparation A (88/826) is very stable.The high purity streptokinase preparation, coded 88/826, has been established by the World Health Organisation as the 2nd International Standard for Streptokinase, with an assigned potency of 700 i.u. per ampoule.

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A Collaborative Study to Establish an International Standard for Alpha-Thrombin

Thrombosis and Haemostasis ◽

10.1055/s-0038-1648464 ◽

1992 ◽

Vol 67 (04) ◽

pp. 424-427 ◽

Cited By ~ 3

Author(s):

P J Gaffney ◽

A B Heath ◽

J W Fenton II

Keyword(s):

Elevated Temperatures ◽

Collaborative Study ◽

World Health Organisation ◽

Significant Loss ◽

Thrombin Inhibitors ◽

World Health ◽

Expert Committee ◽

International Standard ◽

Assay Procedure ◽

And Control

SummarySince 1975 an International Standard for Thrombin of low purity has been used. While this standard was stable and of value for calibrating thrombins of unknown potency the need for a pure a-thrombin standard arose both for accurate calibration and for precise measurement of thrombin inhibitors, notably hirudin. An international collaborative study was undertaken to establish the potency and stability of an ampouled pure a-thrombin preparation. A potency of 97.5 international units (95% confidence limits 86.5-98.5) was established for the new a-thrombin standard (89/ 588) using a clotting-assay procedure. Stability data at various elevated temperatures indicated that the standard could be transported and stored with no significant loss of potency.Ampoules of lyophilised a-thrombin (coded 89/588) have been recommended as an International Standard for a-thrombin with an assigned potency of 100 international units per ampoule by the International Society for Thrombosis and Haemostasis (Thrombin and its Inhibitors Sub-Committee) in Barcelona, Spain in July 1990 while the Expert Committee on Biological Standardisation and Control of the World Health Organisation will consider its status at its next meeting in Geneva in 1991.

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PHYSICAL ACTIVITY RELEASES TISSUE PLASMINOGEN ACTIVATOR FROM EXERCISING PARTS OF BODY

10.1055/s-0038-1643117 ◽

1987 ◽

Author(s):

I Keber ◽

K Potisk ◽

D Keber ◽

M Stegnar ◽

N Vene

Keyword(s):

Physical Activity ◽

Plasminogen Activator ◽

Tissue Plasminogen Activator ◽

Fibrinolytic Activity ◽

Venous Occlusion ◽

Clot Lysis ◽

Lysis Time ◽

Tissue Plasminogen ◽

Euglobulin Clot Lysis Time ◽

The Difference

To determine the origin of tissue plasminogen activator (t-PA) release during physical activity, we studied the separate and combined effects of venous occlusion and acute physical activity on t-PA release in arm and leg. In 15 healthy volunteers 20 min venous occlusions of arm and leg were performed simultaneously before physical activity ( maximal stress testing on treadmill)(occlusion I), immediately after physical activity and 45 min later (occlusion II). Blood samples were drawn from unoccluded arm before occlusion and after physical activity, and from occluded arm and leg after occlusion. Fibrinolytic activity was measured by euglobulin clot lysis time (ECLT) and t-PA activity assay. The amount of released t-PA during different stimuli (fibrinolytic potential) was calculated as the difference between post- and prestimulation fibrinolytic activity. Before physical activity there was a great increase in fibrinolytic activity due to t-PA in the occluded arm but no increase in the occluded leg. Physical activity itself caused a similar increase of systemic fibrinolytic activity as arm occlusion locally. After physical activity arm occlusion evoked equally good response than before it. Fibrinolytic activity during leg occlusion behaved differently: there was an increase in t-PA activity in the occluded leg which persisted one hour after physical activity, when systemic fibrinolytic activity already fell to initial level.These results demonstrated that walking and running triggered t-PA release from the leg vessels. Since leg occlusion was not a stimulus for t-PA release, it served only as a method to demonstrate the effect of physical activity.

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