Assay for plasminogen activator inhibitor-1 and tissue plasminogen activator activity
AssigneeBeth Israel Deaconess Medical Center, Inc.
InventorsJan McDonagh, Myoung H. Lee, Marcin J. Mankowski
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Abstract
The invention is based upon the discovery that PAI-1 activity of a sample can be measured with sensitivity and correlation to in vivo activity without the use of standard curves. The assay determines the PAI-1 activity of a sample upon utilizing the second order rate equation for the reaction of PAI-1 and t-PA, as measured by their activities, in that sample.
Claims16
A method for obtaining an initial activity of plasminogen activator inhibitor-1, an initial activity of tissue plasminogen activator, or a half-life of tissue plasminogen activity in a sample comprising the steps of:
- (a) measuring activity of tissue plasminogen activator in the sample as a function of time;
- and
- (b) obtaining a value of (PAI)0, (t-PA)0 or ½ (t-PA)0;
- from formula:
- kt=−1/((PAI)0−(tPA)0)ln{(tPA)0[(PAI)0−(tPA)0+(tPA)]}/(PAI)0(tPA)
- wherein (PAI)0 is the initial activity of plasminogen activator inhibitor-1 in the sample;
- (tPA)0 is the initial activity of tissue plasminogen activator in the sample;
- (tPA) is an activity of tissue plasminogen activator at time t;
- and
- the half-life of tissue plasminogen activator in the sample is a value for t wherein (tPA) is ½ (t-PA)0;
- k is a second order rate constant for a reaction:
A method for obtaining an initial activity of plasminogen activator inhibitor-1, an initial activity of tissue plasminogen activator, or a half-life of tissue plasminogen activity in a sample, wherein the sample is a body fluid, comprising the steps of:
- (a) adding tissue plasminogen activator to the sample;
- (b) acidifying the sample;
- (c) contacting a first preselected amount of the sample with plasminogen, thereby obtaining a mixture:
- (d) maintaining the mixture under conditions sufficient to permit tissue plasminogen activator-catalyzed conversion of plasminogen to plasmin;
- (e) measuring the plasmin formed in step (d), thereby measuring activity of tissue plasminogen activator at a first time, t;
- (f) repeating steps (c) through (d) at least at two different times, t;
- (g) obtaining a value of (PAI)0, (tPA)0 or ½ (t-PA)0 from a formula:
- kt=−1/((PAI)0−(tPA)0)ln{(tPA)0[(PAI)0−(tPA)0+(tPA)]}/(PAI)0(tPA)
- wherein (PAI)0 is the initial activity of plasminogen activator inhibitor-1 in the sample;
- (tPA)0 is the initial activity of tissue plasminogen activator in the sample;
- (tPA) is an activity of tissue plasminogen activator at time t;
- and
- the half-life of tissue plasminogen activator in the sample is the value for t wherein (tPA) is ½ (t-PA)0;
- k is a second order rate constant for a reaction:
Dependencies are inferred from the claim text.