Objectives Abnormal proliferation and migration of vascular smooth muscle cells (VSMCs) are involved in carotid artery stenosis. The purpose of this study was to investigate the diagnostic value of serum miR-28-5p in asymptomatic carotid artery stenosis and its regulation on the proliferation and migration of VSMCs. Methods Serum miR-28-5p levels in 65 healthy controls and 68 asymptomatic carotid artery stenosis patients were detected by qRT–PCR. The receiver-operating characteristic curve was applied to elucidate the diagnostic value of serum miR-28-5p for carotid artery stenosis patients. The specificity of miRNA targets was detected by luciferase reporter assay. CCK-8 and Transwell assay were applied to detect proliferation and migration of cells. Pearson correlation test was used to investigate the correlation between Forkhead box subclass O 1 (FOXO1) and serum miR-28-5p. Results Serum miR-28-5p was significantly reduced in asymptomatic carotid artery stenosis patients. Moreover, miR-28-5p could distinguish asymptomatic carotid artery stenosis patients from healthy controls, with sensitivity and specificity of 86.8% and 81.5%, respectively, indicating its high diagnostic value. The overexpression of miR-28-5p inhibited the proliferation and migration of VSMCs, while inhibition of miR-28-5p resulted in the opposite effect. What is more, FOXO1, a direct target of miR-28-5p, was significantly increased in asymptomatic carotid artery stenosis patients. Inhibition of miR-28-5p in VSMCs reversed the reduction of FOXO1 levels in patients. Conclusions miR-28-5p is a valuable diagnostic biomarker for asymptomatic carotid artery stenosis and can affect the proliferation and migration of VSMCs by regulating FOXO1.

Objectives To study the impact of respiratory frequency on HRV and discuss how to exclude it. Methods 12 healthy male rabbits aged 4-5 months and weighting 2.5-3.0 kg were selected. The Rabbits respiratory control system was established. ECG, instant blood pressure and respiratory waveform under different respiratory frequency (RF) (40 bpm,50 bpm,60 bpm) were recorded synchronously via SKY-A4 (a three channel electrophysiolograph); HRV & BRS2.0-a HRV analysis system was used to observe the shift of high frequency peak (HFP), and to analyse power spectra density (PSD). Two different analysis methods were adopted to analyse PSD, tHRV (traditional heart rate variability) analysis method with which parameters of different frequency segment were preset; EHRV (enhance heart rate variability) analysis method with which very low frequency were filtered, and HF were located near Fundamental Respiratory Frequency (FRF). Comparisons between the results of the two methods were made. Results The shift of HFP: RF 50 bpm, the HFP was located at the conjunction of LF segment and HF segment; RF 40 bpm, HFP would be shifted into the LF segment; RF 60 bpm, the total HFP would be shifted into HF segment. Comparison between tHRV and eHRV results: tHRV results:compared with RF 50 bmp, RF 40 bpm HF, HFnorm were decreased, LF, LFnorm, LF/HF were increased; RF 60 bpm seems increase HF (t =-3.477, P = 0.005), HFnorm (t =-2.903, P = 0.013), decrease LF/HF (t = 2.500, P = 0.028). eHRV results: there was no significant difference was fund between different RF PSD. Conclusions RF slow down would shift HFP to relatively low frequency, sometimes to LF segment, which would increase LF and decrease HF. Enhanced HRV analysis could exclude this influence.

Objectives To discuss the relationship between vagus nerve and heart rate variability (HRV). Methods 12 healthy rabbits were selected and anaesthetized, ventilation was used to control respiratory parameters, tide volume preset 10 mL/kg, respiratory frequency preset 50 beat per min, carotid compression transducer was used to monitor blood-pressure. ECGs of pre and post vagotomy were collected and analysed. Results RRI cyclical change pre and post vagotomy coincided with the respiratory cycle. Peak of RRI and respiratory power spectral density post vagotomy were shifted right (0.19 ± 0.02 vs 0.20 ± 0.03, P < 0.01), but they still located at the same frequency. HF post-vagotomy were significantly decreased (0.31 ± 0.21 vs 0.48 ± 0.24, P < 0.01), LF/HF post-vagotomy were significantly increased (0.59 ± 0.47 vs 0.27 ± 0.30, P < 0.01), compared with HF and LF/HF pre-vagotomy. Conclusions Vagus nerve could affect respiratory sinus arrhythmia (RSA), but it was not the unique pathway attribute to RSA. High frequency power (HF) could reflect the function of vagus, but could not totally represent the tense of vagus nerve.