Objective To study the characteristics of infarct-related-artery (IRA) in acute high lateral wall myocardial infarction and to give clinical clue for deducing the location of coronary artery lesions. Methods Ninety-six patients with acute high lateral wall myocardial infarction (77 males, 19 females, mean age 57.3?10.7 years) were enrolled in the study. They all had infarction for the first time and were confirmed to have single vessel coronary artery disease by coronary angiography. The patients were divided into 3 groups according to the ECG changes at the onset of infarction. The first group (group A) was simple high lateral wall infartion (23 cases). The second one (group B) was high lateral with anterior wall infarction (58 cases, among them 27 cases with anteral-septal infarction and the other 31 with extensive anterior infarction). The third group (group C) was high lateral with lateral wall infarction (15 cases). Lesion characteristics of IRA were analyzed. Results The infarction-related lesions were mainly on left anterior descending arteries in group B (56/58), and on left circumflex in group C (13/15). But those in group A could be on either diagonal (12/23) or left circumflex (11/23). The difference of distribution of IRA among these groups was statistically significant (P

Polymyxin B and polymyxin E (colistin) are presently considered the last line of defense against human infections caused by multidrug-resistant Gram-negative organisms such as carbapenemase-producer Enterobacterales, Acinetobacter baumannii, and Klebsiella pneumoniae. Yet resistance to this last-line drugs is a major public health threat and is rapidly increasing. Polymyxin S₂ (S₂) is a polymyxin B analogue previously synthesized in our institute with obviously high antibacterial activity and lower toxicity than polymyxin B and colistin. To predict the possible resistant mechanism of S₂ for wide clinical application, we experimentally induced bacterial resistant mutants and studied the preliminary resistance mechanisms. Mut-S, a resistant mutant of K. pneumoniae ATCC BAA-2146 (Kpn2146) induced by S₂, was analyzed by whole genome sequencing, transcriptomics, mass spectrometry and complementation experiment. Surprisingly, large-scale genomic inversion (LSGI) of approximately 1.1 Mbp in the chromosome caused by IS26 mediated intramolecular transposition was found in Mut-S, which led to mgrB truncation, lipid A modification and hence S₂ resistance. The resistance can be complemented by plasmid carrying intact mgrB. The same mechanism was also found in polymyxin B and colistin induced drug-resistant mutants of Kpn2146 (Mut-B and Mut-E, respectively). This is the first report of polymyxin resistance caused by IS26 intramolecular transposition mediated mgrB truncation in chromosome in K. pneumoniae. The findings broaden our scope of knowledge for polymyxin resistance and enriched our understanding of how bacteria can manage to survive in the presence of antibiotics.