| Objective To evaluate the serumal IMA levels in healthy persons of different genders, different ages and different serumal albumin levels, then to determine an appropriate cut-off value; to detect its early diagnostic values in acute coronary syndromes; to find out the relationships between IMA,hypertension and virus myocarditis;to set up a method of purification for human serumal albumin, to study the secondary structure of the aim protein ,then to find the formation mechanisms of IMA.Methods (1) To measure the serumal IMA levels by the albumin cobalt binding test (ACB) in the research, 2899 serumal specimens were detected, including 1004 patients with ACS which included 543 patients with UA and 461 patients with AMI; 535 patients with acute chest pain coming to the emergency department for the first time, including 198 patients of ACS and 337 patients as follow-ups; 117 persons with hypertesion; 95 persons with viral myocarditis; 110 patients with acute CI and 1038 healthy persons as control. (2) cTnI were assayed by immumofluorescence method for ACS patients, and ECG were recorded simultaneously. (3) IMA was purified by salting out and ion exchange chromatography. Then the purified protein was taken to analyze its secondary structures by circular dichroism (CD) spectra measurement.Results(1) The average IMA level in 1038 healthy persons as control was 0.33±0.074 absorbance units(ABSU). There were no significant differences in genders, in ages or in different concentrations of serumal albumin of control(P>0.05).The 95 percent medical reference range of IMA was lower than 0.50ABSU. (2) At a cutoff point of 0.50ABSU, sensitivity and specificity of IMA were 84.4% and 96.1% respectively. The negative and positive predictive value were 95.6% and 79.2% respectively. The Youden's index of IMA was 0.795 with an agreement rate of 89.0%. (3) The average IMA level in 1004 patients with ACS was 0.55±0.12ABSU, which was higher than that of control's(P<0.05). (4) The average IMA level in 535 patients with acute chest pain including 198 patients with acute ACS and 337 follow-up patients was 0.47±0.12ABSU, there were significant differences between the two groups(P<0.05). (5) The average IMA level in 198 patients with ACS was 0.53±0.11 ABSU during the first hour they presented, increasing to a peak after 24 hours following their hospitalization. Then they began to descend, and the average IMA level after 14 days was significantly lower than either the first hour or the peak(0.49±0.12ABSU vs0.53±0.11ABSU vs 0.58±0.11 ABSU)(P<0.05).(6) IMA had a higher sensitivity than cTnI or ECG during the first hour the patients presented(78.3% vs 43.9% vs 52.5%)(P<0.05). When IMA was combined with cTnI, the sensitivity was higher than that of either IMA or cTnI or ECG alone(89.9% vs 78.30%, 43.9%, 52.5%). When IMA was combined with ECG, the diagnostic positive rate rised to 92.4 %, and rised to 99.0% if all of them combined together. (7) The IMA levels in patients with hypertension were 0.34±0.073 ABSU, there were no significant differences between hypertension group and the control. IMA in patients with viral myocarditis was 0.39±0.11ABSU, there were significant differences between myocarditis group and the control. (8) The average IMA level in 110 patients with acute cerebral infarction was significantly higher than that of control's(0.55±0.095ABSU vs 0.33±0.074ABSU)(P<0.05), and the difference was not statistically significant between that in patients with cerebral infarction and that of ACS(P>0.05). (9) The results of CD spectra measurement revealed that the secondary structure of IMA was not obviously changed, while the average percentages ofα-helixes and random coil decreased and the average percentages ofβ-turn andβpleated sheets increased a bit in ACS patients.Conclusion IMA has a high negative predictive value, sensitivity and speciality in the early diagnosis of ACS, and the clinical sensitivity of IMA is higher than that of cTnI and ECG. A combination of IMA and cTnI or IMA and ECG will significantly improve the sensitivity in the early diagnosis of myocardial ischemia. IMA also increases in the presence of non-cardiogenic ischemia, so consideration should be taken into when explaining those positive results. The results of CD spectra measurement revealed that the secondary structure of IMA was not obviously changed, while the average percentages ofα-helixes and random coil decreased a bit and the other two kinds of structures increased in ACS patients.This may correlate with its formation mechanism. |
PDF Full Text Request