The sensitivity of cardiac troponin testing for diagnosing acute myocardial infarction(AMI)varies over time from chest pain onset.This study aimed to determine the diagnostic performance of point-of-care testing cardiac troponin T(POCT-cTnT)at different time intervals post-symptom onset to refine rapid rule-out approaches for AMI.Methods This retrospective study included 6,024 patients presenting with chest pain from January 2018 to December 2022.POCT-cTnT and central lab cTnI levels were measured on admission.Receiver operating charac-teristics analysis stratified by time windows assessed the accuracy of POCT-cTnT for diagnosing AMI.Results The overall AUC of POCT-cTnT for diagnosing AMI was 0.826(95%CI:0.816～0.836),with a sensitivity of 72.81%and a specificity of 86.26%.According to the time intervals of chest pain onset(＜3 hours,3～6 hours,6～12 hours,12～24 hours,24～72 hours,and≥72 hours),the AUC values for groups after 6～12 hours were 0.918,0.928,0.920 and 0.908,respectively,with no statistically significant difference(P＞0.05),but all were higher than the groups within 6 hours(P＜0.001).According to the time of chest pain onset,the AUC for the≥8h group was 0.921,with a negative predictive value(NPV)of 98.1%and a negative likelihood ratio(-LR)of 0.11.Its AUC was higher than those of the≥3 h,≥2 h,≥1 h,and overall groups(P＜0.05),but there was no statistically significant differ-ence compared with the groups after≥4 h(P＞0.05).Conclusions Chest pain onset time has a certain impact on the performance of a single POCT-cTnT test for diagnosing AMI.The duration from chest pain onset to hospital admission combined with POCT-cTnT test may improve the reliability in diagnosing AMI.Specifically,a single POCT-cTnT test at four hours after chest pain onset,especially eight hours after chest pain onset,can diagnose or exclude AMI.

Arginine kinase (AK) is a key enzyme in energy metabolism of invertebrates and plays an important regulatory role in the life activities such as growth and development, nutrition utilization, immune resistance and stress response. Arginine kinase of Bombyx mori (BmAK) is related to the energy balance and anti-NPV process, but there is little research on its molecular structure and enzymatic properties. We cloned the ORF sequence of BmAK gene, and analyzed chromosomal localization, genomic structure, mRNA structure, secondary and tertiary structure. Phylogenetic analysis indicated that AK was highly conserved in evolution. Soluble recombinant BmAK was obtained by prokaryotic expression, and purified by Ni-NTA affinity chromatography. The circular dichroism spectroscopy showed that BmAK contained α-helix structures, and its α-helix structures were relatively stable in the pH range between 5 and 10. Enzyme activity analysis showed that the optimum temperature of BmAK was 30 ℃ and the optimum pH of BmAK was 7.5. The optimal temperature of BmAK was 25 ℃. Between 15 ℃ and 30 ℃, the structure and activity of BmAK was relatively stable. The structure of BmAK was relatively stable at pH 7.0. Our findings reveal the structure and function of BmAK to develop novel green safe and environmentally friendly insecticides.