Study On The Actin,cTnT And Fn For The Diagnosis Of Myocardial Ischemia

Objective: The patients with sudden coronary death (SCD) iscommonly seen in forensic practice, accounting for 80% of sudden cardiacdeath. The postmortem diagnosis of SCD by pathologists is difficult,particularly when death occurs within one to two hours after ischemicinsult. Myocardial ischemia is the primary reason of SCD that is theemphases of forensic study. We intend to detect the expression of actin(HHF35), cTnT and fibronectin(Fn) in the autopsied hearts of acutemyocardium infarction(AMI) and suspected ischemic myocardium in orderto find some sensitive, reliable biomarkers for the forensic diagnosis ofmyocardium ischemia. Method: The immunohistochemical method (the two-step) was usedto detect the expression of protein Actin, cTnT and Fn in the autopsiedhearts of AMI, suspected ischemic myocardium and normal human heartsin 20 cases respectively. The samples were also subjected tohematoxylin-basci fuchsin-picric(HBFP). And the depletion areas ofHHF35, cTnT and the positive area Fn were measured by computer imageanalysis. Results: There were depletive expressions of Actin in myocardiumplasma of 19 cases in AMI and 16 cases in suspected myocardial ischemia,that of cTnT were 16 cases in AMI and 14 cases in suspected myocardialischemia in contrast to no depletion in the cases of normal hearts. Thedepletion areas of HHF35 were 144935.80±1031.22 and 94360.00±1330.48 respectively, that of cTnT were 126771.60 ± 1071.57 and114651.70±728.54 respectively, both of them were in per 200x high powerfield. Besides there was positive expression in the myocardium of 18 casesin AMI and 15 cases in suspected myocardial ischemia while there wasnegative expression in the normal hearts. The positive area were 72736.78±1684.78 and 13787.44±1428.79 in per 200x high power field. Therewere positive correlation between Fn and HHF35 or cTnT. The correlationratio were 0.496 and 0.527. There were significant difference among thethree groups (P<0.01), there was also signific difference between AMI andsuspected myocardial ischemia(P<0.05). Conclusion: 1. As myocardial structural protein, actin has simple structure andsmall molecular weight. It can rapidly flow out of cardiomyocytes whenmyocardium suffers ischemia insult. So it is a reliable biomarker. 2. cTnT is adjustive protein of muscle contract system and has organicspecificity. So it is a specifically marker. 3. Fn is an irreversible biomark of myocardial damage. It is positivecorrelation between Fn and actin or cTnT. Fn degradation can changemyocardial ultrastructure which make myocardial structural proteindepleted. 4. HBFP is a useful method to diagnose myocardial ischemiaassociated with HE and immunohistochemical stain.