Fifty randomly selected healthy volunteers were also enrolled in the validation phase as a healthy control group. were also enrolled in the validation phase as a healthy control group. In the discovery/screening phase, 17 out of 20 randomly selected phage clones exhibited specific reaction with purified sera IgG from the PMI group, among which 11 came from the same phage clone with inserted peptide sequence (named PMI-1). In the validation phase, phage ELISA showed that serum IgG from 90% of patients in the PMI group had a positive reaction with PMI-1; in contrast, only 14% and 6% of patients in the non-PMI group and the healthy control group had a positive reaction with PMI-1, respectively. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy of the PMI-1 phage clone to preoperatively identify patients who would develop PMI after CABG were 90.0%, 86.0%, 86.5, 89.5% and 88.0%, respectively. The absorbance value of the PMI-1 phage clone showed statistically significant correlation with the peak postoperative serum cardiac troponin I level (r?=?0.349, pairwise comparisons using Tukey’s tests. Categorical variables were compared with Chi-square assessments or Fisher’s exact assessments. A Lamotrigine two-tailed (named PMI-2). Using the NCBI Blast software, we searched for the identified peptide sequence in different protein databases including Swissprot and Protein Data Lender, and found that both PMI-1 and PMI-2 had no significant homology with other protein sequences (score 50). Chessboard titration was applied to determine the optimal reaction concentrations for the positive phage clones and sera IgG from the PMI group. The optimal coating Lamotrigine concentrations were 1011 pfu/well and 1012 pfu/well for the PMI-1 and the PMI-2 phage clones, respectively. The optimal dilution of sera IgG from the PMI group was 1100 for both PMI-1 and PMI-2. Open in a separate window Physique 2 Inserted DNA sequence in positive peptide phage clones.After 3 rounds of biopanning, 20 peptide phage clones were randomly picked and reacted with sera IgG from patients with PMI after coronary artery bypass grafting. Phage clones were considered positive when their absorbance values in phage ELISA were above the cutoff value (0.494), which was set to 2 times of the absorbance value of the negative control (NC, black bar) at 450 nm. C1, C2, C5, C7, C10, C12, C13, C15, C16, C18 and C19 positive phage clones (green bars) had the same inserted DNA sequence (named PMI-2). The unfavorable phage clones were shown in red bars. The Lamotrigine two single positive phage clones were shown in white bars. Table 3 Phage clone enrichment. pairwise comparisons using Tukey’s assessments. Categorical variables were compared with Chi-square assessments. PMI, postoperative myocardial infarction; a em p /em 0.05 vs. Healthy control; b em p /em 0.05 vs. Non-PMI. As shown in Table 5, using the non-PMI group as a control, sensitivity of the PMI-1 and the PMI-2 phage clones to preoperatively identify patients who would develop PMI after CABG were 90.0% and TNFSF13 96.0%, specificity 86.0% and 48.0%, PPV 86.5% and 64.9%, NPV 89.5% and 92.3%, and accuracy 88.0% and 72.0%, respectively. Using the healthy control group as a control, sensitivity of the PMI-1 and the PMI-2 phage clones to preoperatively identify patients who would develop PMI after CABG were 90.0% and 96.0%, specificity 94.0% and 96.0%, PPV 93.8% and 96.0%, NPV 90.4% and 96.0%, and accuracy 92.0% and 96.0%, respectively. Table 5 Predictive validity of PMI-1 and PMI-2. thead Positive phage cloneControl groupSensitivity (%)Specificity (%)PPV (%)NPV (%)Accuracy (%) /thead PMI-1Non-PMI (n?=?50)90.086.086.589.688.0Healthy control (n?=?50)90.094.093.890.492.0PMI-2Non-PMI (n?=?50)96.048.064.992.372.0Healthy control (n?=?50)96.096.096.096.096.0 Open in a separate window Note: All indicator values were expressed in percentage: sensitivity?=?true positive/(true positive+false unfavorable); specificity?=?true negative/(true unfavorable+false positive); positive predictive value (PPV)?=?true positive/(true positive+false positive); unfavorable predictive value (NPV)?=?true negative/(true unfavorable+false unfavorable); accuracy?=?(true positive+true unfavorable)/(true positive+false unfavorable + true unfavorable+false positive). PMI, postoperative myocardial infarction. In the validation phase, the absorbance value of the PMI-1, but not the PMI-2 phage clone showed statistically significant correlation with the peak postoperative serum cTnI level (for PMI-1, r?=?0.349, em p /em ?=?0.012; for PMI-2, r?=?0.254, em p /em ?=?0.085) in the PMI group. Discussion PMI is one of the most severe complications in patients undergoing cardiac surgery. Early diagnosis of PMI is usually important for optimal postoperative patient management C. However, PMI is usually a multifactorial disorder with significant inter-patient variability poorly predicted by clinical and procedural factors . No preoperative biomarker is currently available for predicting PMI after cardiac surgeries. In this study, we for the first time identified a mimic peptide with high validity in predicting preoperatively whether a patient would develop.