Electrochemical detection of ischemia
View Patent ↗The subject invention comprises electrochemical methods and devices for in vitro detection of an ischemic event in a patient sample. Following addition of a known amount of a transition metal ion to the patient sample, electrodes are used to measure the current or potential difference of non-sequestered transition metal ion in the sample. The amount of non-sequestered transition metal ion in the sample reflects the degree of modification to albumin that is the result of an ischemic event.
1. A method for in vitro detection or measurement of albumin derivatives, which can be diagnostic of an ischemic event, said method comprising:
a) providing a patient sample comprising albumin and/or derivatives thereof in a vessel that is connected to an electrochemistry apparatus;
b) operating the electrochemistry apparatus to utilize an electrochemical technique;
c) optionally measuring a background characteristic electrochemical output signal of the sample;
d) adding a known amount of a transition metal ion to the sample, whereby at least some of the ion binds to albumin metal sequestering sites and remaining ion is non-sequestered;
e) optionally adding an indicator or amplifier to the sample to bind to the non-sequestered ion;
f) measuring a characteristic electrochemical output signal associated with the non-sequestered ion;
g) optionally using a standard curve to convert the measured output signal of step (f) to a converted value;
whereby the measured electrochemical output signal or the converted value, if it exceeds a predetermined value, can be diagnostic of an ischemic event.
2. The method of claim 1 , wherein the known amount of metal ion is an excess amount.
3. The method of claim 1 , wherein the characteristic electrochemical output signal is selected from the group consisting of current and voltage.
4. A method for in vitro detection or measurement of albumin derivatives, which can be diagnostic for an ischemic event, said method comprising:
a) providing a patient sample comprising albumin and/or derivatives thereof in a vessel having a reference electrode and a working electrode, said electrodes being operably connected to a potentiostat;
b) operating the potentiostat to apply a potential to the sample;
c) optionally offsetting a background current from redox reactions in the sample to zero;
d) adding a known amount of a transition metal ion to the sample, whereby at least some of the ion binds to albumin metal sequestering sites and remaining ion is non-sequestered by albumin;
e) optionally providing an indicator or amplifier to the sample to bind to the non-sequestered metal ion;
f) permitting the reaction of ion and albumin to reach equilibrium or a predetennined processing time; and
g) measuring the current associated with the non-sequestered ion;
h) optionally using a standard curve to convert the measured current to a converted value;
whereby the measured current or converted value, if it exceeds a predetermined value, can be diagnostic of an ischemic event.
5. The method of claim 4 , wherein the known amount of metal ion is an excess amount.
6. The method of claim 4 wherein said vessel further comprises an auxiliary electrode in said vessel that is operably connected to said potentiostat.
7. The method of claim 6 , wherein the known amount of metal ion is an excess amount.
8. The method of claim 4 wherein said working electrode further comprises an indicator or amplifier to bind to non-sequestered metal ion.
9. The method of claim 4 , wherein said diagnosed ischemic event is cardiac ischemia.
10. The method of claim 4 , wherein said diagnosed ischemic event is silent ischemia.
11. The method of claim 4 , wherein the diagnosed ischemic event is angina.
12. The method of claim 4 , wherein the diagnosed ischemic event is myocardial infarction.
13. The method of claim 4 , wherein the diagnosed ischemic event is temporally-limited isehemia.
14. The method of claim 4 , wherein the diagnosed ischemic event is bowel ischemia.
15. The method of claim 4 , wherein the diagnosed ischemic event is brain ischemia.
16. The method of claim 4 , wherein the diagnosed ischemic event is placental insufficiency.
17. The method of claim 4 , wherein said diagnosis of the ischemic event is used to evaluate efficacy of an in-situ coronary stent.
18. The method of claim 4 , wherein said diagnosis of the ischemic event is used to evaluate efficacy of percutaneous cardiac intervention.
19. The method of claim 4 , wherein said diagnosis of the ischemic event is used to evaluate efficacy of drug therapy.
20. A method of detecting or measuring exercise-induced ischemia by determining the level of ischemia in a patient during exercise, and before exercise, after exercise or both, and comparing said levels, wherein ischemic events are detected or measured using the method of claim 4 .
21. A method for in vitro detection or measurement of albumin derivatives which may be diagnostic for an ischemic event, said method comprising:
a) providing a patient sample comprising albumin and/or derivatives thereof in a vessel having an ion selective electrode and a reference electrode, said electrodes being operably linked to an electrostat or a voltmeter, said ion selective electrode comprising a barrier that is selectively permeable to a transition metal ion;
b) operating the electrostat or voltmeter to measure the potential difference between the reference electrode and the ion selective electrode in contact with the sample;
c) optionally offsetting a background potential difference of the sample;
d) adding a known amount of said transition metal ion to the sample, whereby at least some of the ion binds to albumin metal sequestering sites and remaining ion is non-sequestered;
e) optionally providing an indicator or amplifier to the sample to bind with the non-sequestered metal ion;
f) permitting the non-sequestered metal ion to cross the membrane of the ion selective electrode; and
g) measuring a voltage associated with an ion activity difference across the ion selective electrode's barrier;
h) optionally using a standard curve to convert the measured voltage of step (g) to a converted value;
whereby the measured voltage or the converted value, if it exceeds a predetermined value, can be diagnostic of an ischemic event.
22. The method of claim 21 , wherein the diagnosed ischemic event is cardiac ischemia.
23. The method of claim 21 , wherein said diagnosed ischemic event is silent ischemia.
24. The method of claim 21 , wherein the diagnosed ischemic event is angina.
25. The method of claim 21 , wherein the diagnosed ischemic event is myocardial infarction.
26. The method of claim 21 , wherein the diagnosed ischemic event is temporally-limited ischemia.
27. The method of claim 21 , wherein the diagnosed ischemic event is bowel isohemia.
28. The method of claim 21 , wherein the diagnosed ischemic event is brain isehemia.
29. The method of claim 21 , wherein the diagnosed ischemic event is placental insufficiency.
30. The method of claim 21 , wherein said diagnosis of the ischemic event is used to evaluate the efficacy of an in-situ coronary stent.
31. The method of claim 21 , wherein said diagnosis of the ischemic event is used to evaluate the efficacy of a percutaneous cardiac intervention.
32. The method of claim 21 , wherein said diagnosis of the ischemic event is used to evaluate the efficacy of drug therapy.
33. A method of detecting or measuring exercise-induced ischemia by determining the level of ischemia in a patient during exercise, and before exercise, after exercise or both, and comparing said levels, wherein ischemic events are detected or measured using the method of claim 21 .