AIM: To assess the effect of RNAi on suppressing the exogenous reporter gene expression in mammalian neurons,and explore the effect of siRNA quantitation on interference efficiency.METHODS: Exogenous green fluorescent protein(GFP) expression vector was transferred into neuro-2a cells,and then the small interference RNA targeting GFP mRNA(siGFP) synthesized by transcription in vitro at three different concentration was used in this experiment.RESULTS: The results showed that the neuro-2a cells can be transfected efficiently and siGFP can inhibit GFP expression greatly.CONCLUSION: RNAi can be applied into mammalian neurons successfully.The research on siRNA quantitation will provide technique support for studying the gene function of neurons in the future.

Objective:To observe heart rate circadian rhythm in patients with chronic kidney disease (CKD) stage 5 and to analyze the effects of parathyroidectomy (PTX) on heart rate circadian rhythm in severe secondary hyperparathyroidism (SHPT) patients.Methods:A cross-sectional observation was performed in 213 patients with CKD stage 5 and 96 controls, and the patients were divided into those with severe SHPT (PTX group, n=70) and without severe SHPT (non-PTX group, n=143). Forty-six PTX patients were followed up prospectively. The baseline data were compared among these groups. Holter electrocardiogram was performed for each participant. Non-dipping heart rate was defined as night/day heart rate ratio greater than 0.9. Multiple linear regression analysis was used to analyze the related factors of heart rate circadian rhythm in patients with CKD stage 5. Results:The 24-hour, daytime and nighttime mean heart rate in patients with CKD stage 5 were all higher than those in controls, especially in PTX group (all P<0.05). The night/day heart rate ratios of controls and CKD stage 5 patients were (0.81±0.08) and (0.91±0.08) respectively ( P<0.01). Correlation analysis showed 24-hour and daytime or nighttime mean heart rate in patients with CKD stage 5 were positively correlated with serum levels of phosphorus and ln(alkaline phosphatase), while nighttime mean heart rate and night/day heart rate ratio were positively related with serum intact parathyroid hormone level. After adjusting with postoperative follow-up period (median time: 10.9 months), 24-hour and nighttime mean heart rate, and night/day heart rate ratio in PTX patients all decreased significantly (all P<0.01). Conclusions:Heart rate is increased and circadian rhythm is abnormal in patients with CKD stage 5, which are related with mineral and bone disorder. PTX significantly decreases 24-hour and nighttime mean heart rate in severe SHPT patients, and improves the heart rate circadian rhythm.

Objective:To investigate the predictive value of abnormal heart rate circadian rhythm for all-cause mortality in stage 5 chronic kidney disease (CKD 5) patients.Methods:The retrospective study was performed in CKD 5 patients enrolled from the First Affiliated Hospital of Nanjing Medical University (Jiangsu Province Hospital) and the Affiliated BenQ Hospital of Nanjing Medical University from February, 2011 to December, 2019. A total of 159 healthy volunteers were enrolled as the healthy control group during the same period. The circadian rhythm of heart rate was monitored by 24-hour Holter. Related indices (including 24-hour, daytime and nighttime mean heart rate, night/day heart rate ratio, 24-hour maximum heart rate, 24-hour minimum heart rate and difference between maximum and minimum of 24-hour heart rate) were calculated. Non-dipping heart rate was defined as night/day heart rate ratio greater than 0.9. Cox regression model was used to analyze the risk factors of all-cause mortality in CKD 5 patients. Kaplan-Meier survival curve and Log-rank test were used to compare the differences of cumulative mortality between high ratio group (night/day heart rate ratio>0.91) and low ratio group (night/day heart rate ratio≤0.91). The nonlinear relationship between night/day heart rate ratio and all-cause mortality was analyzed by restricted cubic spline plot. Time-dependent receiver operating characteristic (ROC) curve was used to analyze the predictive value of night/day heart rate ratio for all-cause mortality in CKD 5 patients.Results:A total of 159 healthy volunteers and 221 CKD 5 patients were included in this study. There were 123 males (55.66%) and the age was (52.72±13.13) years old in CKD 5 patients. The total median follow-up time was 50.0 months. Compared with controls, 24-hour, nighttime mean heart rate, 24-hour minimum heart rate in CKD 5 patients were increased (all P<0.05), furthermore, the night/day heart rate ratio was higher [(0.91±0.09) vs (0.81±0.08), P<0.001], showing "non-dipping heart rate". However, the 24-hour maximum heart rate and the difference between maximum and minimum of 24-hour heart rate in CKD 5 patients were lower than controls (both P<0.05). Multivariate Cox regression analysis showed that the increased night/day heart rate ratio (per 0.1 increase, HR=1.557, 95% CI 1.073-2.258, P=0.020) was an independent influencing factor for all-cause mortality in CKD 5 patients. Kaplan-Meier survival curve analysis showed that the cumulative mortality of the high ratio group was significantly increased than that of the low ratio group (Log-rank test χ 2=7.232, P=0.007). From the restricted cubic spline plot, there was a linear effect between night/day heart rate ratio and all-cause mortality ( P=0.141), and when night/day heart rate ratio was above 0.91, the risk of all-cause mortality was significantly increased in CKD 5 patients. According to time-dependent ROC curve, the accuracy of night/day heart rate ratio in predicting all-cause mortality was 70.90% even when the survival time was up to 70.0 months. Conclusions:The circadian rhythm of heart rate in CKD 5 patients displays "non-dipping" state. High night/day heart rate ratio is an independent influencing factor for all-cause mortality in CKD 5 patients.