[Molecular modifications of troponin I and T detected in serum from patients with acute myocardial infarction].
BACKGROUND
Cardiac troponin I and T (cTnI and cTnT) are specific biochemical serum markers for acute myocardial infarction (AMI). However, cTnI diagnostic assays are plagued by difficulties, resulting in > 20-fold differences in measured values. These discrepancies may result from the release of the numerous cTnI modification products that are present in ischaemic myocardium. The resolution of these discrepancies requires an investigation of the exact forms of the troponins present in the bloodstream of patients after myocardial injury.


METHODS
A Westernblot direct serum analysis protocol was developed that allowed us to detect intact cTnI and a spectrum of up to 11 modified products in the serum from patients with AMI.


RESULTS
We document both a cTnI degradation pattern and the existence of phosphorylated cTnI in serum. The number and extent of these modifications reflect patterns similar to the time profiles of the routine clinical serum markers of total creatine kinase, creatine kinase-MB, and cTnI (determined by ELISA). Data from in vitro experiments, which were undertaken to study the degradation of human recombinant cTnI and cTnT when spiked in serum, indicate that some modification products present in patient serum existed in the myocardium.


CONCLUSIONS
This pilot study defines, for the first time, what forms of cTnI and cTnT appear in the bloodstream of AMI patients, and it clarifies the lack of standardization between different cTnI diagnostic assays.
Atar
Dan
D
H:S Frederiksberg Hospital, kardiologisk klinik E, DK-2000 Frederiksberg. datar@dadlnet.dk
Madsen
Lene Helleskov
LH
Labugger
Ralf
R
VanEyk
Jennifer E
JE
D015415:Biomarkers / Q000097:blood* / Q000737:chemistry; D015153:Blotting, Western / Q000379:methods; D006801:Humans; D009203:Myocardial Infarction / Q000097:blood*; D010766:Phosphorylation; D010865:Pilot Projects; D011237:Predictive Value of Tests; D019210:Troponin I / Q000097:blood* / Q000737:chemistry; D020107:Troponin T / Q000097:blood* / Q000737:chemistry
D015415:Biomarkers; D019210:Troponin I; D020107:Troponin T