Objective To observe the changes of nitric oxide (NO) levels in plasma during cardiopul-monary resuscitation (CPR) and to compare the effects of aminoguanidine (AG) and NG-nitro-L-arginine methyl ester (L-NAME) on CPR. Method This was a prospective, randomized animal study performed at the Function Laboratory of Lanzhou University. Cardiac arrest was electrically induced and was left untreated for 5 min. After performing chest compression for 1 min, 40 domestic rabbits were divided into four groups (n = 10) to receive ei-ther 20 mg/kg AG, 25 mg/kg L-NAME, 0.02 mg/kg epinephrine or 2 ml saline placebo before defibrillation. Successfully resuscitated rabbits were observed for a further 4 h. Hernodynamics variables and cardiac functions were monitored with appropriate instrumentation. Arterial blood NO levels were examined at baseline, at the end of 1 min chest compression and at 15, 30, 60 and 120 min after survival. Repeated measures analysis of variance was used to determine statistical significance between groups. Results During chest compression, the mean + stan-dard deviation coronary perfusion pressure was higher in the AG group (40±10 mmHg) than in the L-NAME group (34±8 mmHg; P =0.001) and was higher in both groups with the control group (20±5 mmHg; both P =0.000). Left ventricular + dp/dtmax and- dp/dtmax were higher in the AG group than in the L-NAME group. In the surviving rabbits, the left ventricular + dp/dtmax and - dp/dtmax were higher in the AG and L-NAME groups than in the epinephrine and control groups and were higher in the AG group (4783±912, 4409±827 mmHg/s)than in the b-NAME group (3554±847, 3398±764 mmHg/s; P = 0.001 and 0.023, respectively). Conclu-sions Both AG and L-NAME increased the coronary perfusion pressure, and improved left ventricular systolic and diastolic function during CPR and prevented post-resuscitation myocardial dysfunction. However, AG was signifi-canfly superior to L-NAME.

Objective:To provide a promising and optimal laboratory susceptibility-testing method for the clinical usage of antibiotic (polymyxin), four susceptibility-testing methods were performed and the broth microdilution (BMD) was chosen as the gold standard.Methods:A total number of eighty-eight nonduplicate clinical Enterobacteriaceae specimes were collected from January to December of 2019 in the First Affiliated Hospital, Fujian Medical University. Among the clinical specimens, of which six strains were positive for mcr-1. The minimal inhibitory concentration (MIC) of polymyxin of the clinical specimens were examined by the following methods: (1) broth microdilution, (2) colistin broth disk elution, (3) Vitek-2?, (4)BD PhoenixTM,(5)commercial broth microdilution. With BMD as reference, essential agreement (EA), categorical agreement(CA), very major error(VME) and major error (ME) of polymyxins for different methods were analyzed. The Kappa-consistency testing, paired Chi-square testing and the Spearman-rank correlation testing were used to analyze the consistency between the four antimicrobial susceptibility testing methods and the gold standard.Results:Taking broth microdilution as reference, the EA of colistin broth disk elution, Vitek-2?, BD PhoenixTM, commercial broth microdilution were 94.32% (83/88), 92.05% (81/88), 90.90% (80/88), and 96.59%(85/88), respectively. The CA of all the four methods were 100% (88/88). No VME and ME were recorded for four methods. Moreover, the consistency between four susceptibility testing methods and the gold standard is acceptable (Kappa values=1, P<0.001, McNemar test P=1 and r>0.5, P<0.05). Conclusions:In the present work, four susceptibility testing methods all met the standards recommended jointly by the Clinical and Laboratory Standards Institute and European Committee on Antimicrobial Susceptibility Testing, of which the performance of the commercial broth microdilution and CBDE fared relatively well. Thus, these four methods could be routinely used in clinical microbiology laboratory of our hospital for colistin and polymyxin B susceptibility testing.