Objectives:Comparative analysis of the beagles acute-phase electrocardiographic,hemodynamic,left ventricular flow field status,and energy consumption characteristics of pacing at different sites of conduction system may help to elucidate the scientific mechanism of left bundle branch pacing(LBBP)as a option of physiological pacing therapy.Methods:Eight healthy adult beagles were used in this study.Initially,an active fixation lead was implanted in the right atrial appendage,followed by implantation of another active fixation lead at the right ventricular apex,distal His bundle,and left bundle septal branch,respectively.After connecting a dual-chamber pacemaker,electrocardiographic and acute phase hemodynamic parameters under sinus rhythm,right ventricular apex pacing(RVAP),distal His bundle pacing(DHBP),and LBBP states were collected and analyzed.Three complete cardiac cycles of standard apical three-chamber color Doppler dynamic images were acquired under vector flow mapping(VFM)mode.Offline analysis was performed on obtained parameters including isovolumic contraction period,rapid ejection period,isovolumic relaxation period,rapid filling period,atrial contraction period,and left ventricular intracavitary energy consumption.These parameters were compared under pacing at different sites and the linear correlations of major parameters were analyzed.Results:The QRS duration of baseline intrinsic sinus rhythm,RVAP,DHBP and LBBP were(45.0±4.0)ms,(98.4±6.2)ms,(50.0±4.5)ms and(62.0±4.7)ms,respectively.The LBBP-QRS duration was significantly wider than intrinsic sinus rhythm and DHBP,but significantly narrower than RVAP(all P<0.01).Compared with baseline AOO mode(the pacing rate was performed at 10 beats/min above the intrinsic heart rate),the change of acute phase maximum left ventricular pressure rise rate(LVdP/dtmax)in RVAP,DHBP and LBBP was([-7.89±5.67]% ),([0.74±2.05]% )and([-0.14±3.59]% ),respectively.There was no significant difference in LVdP/dtmax changes between DHBP and LBBP(P=0.667),but both pacing modalities were significantly better than RVAP(all P<0.01).The average energy consumption of the left ventricle under RVAP was significantly higher than that of intrinsic sinus rhythm,DHBP,and LBBP in isovolumic contraction period,rapid ejection period,isovolumic relaxation period,rapid filling period,and atrial contraction period(all P<0.01).However,there was no statistically significant difference in energy consumption among intrinsic sinus rhythm,DHBP,and LBBP during the above five phases(all P>0.05).DHBP and LBBP did not show a significant increase in the number of left ventricular vortices,vortex area,and circulation intensity compared to intrinsic sinus rhythm,and LBBP did not show a significant increase in vortex area and circulation intensity compared to DHBP.Conclusions:Although LBBP canines significantly prolonged the paced QRS duration,it showed no significant differences in acute phase left ventricular hemodynamics,left ventricular flow field status,and energy consumption compared to intrinsic sinus rhythm and DHBP.Performance of LBBP was superior to RVAP.This study may contribute to revealing the theoretical basis of LBBP as a feasible physiological pacing therapy.

Objectives:Comparative analysis of the beagles acute-phase electrocardiographic,hemodynamic,left ventricular flow field status,and energy consumption characteristics of pacing at different sites of conduction system may help to elucidate the scientific mechanism of left bundle branch pacing(LBBP)as a option of physiological pacing therapy.Methods:Eight healthy adult beagles were used in this study.Initially,an active fixation lead was implanted in the right atrial appendage,followed by implantation of another active fixation lead at the right ventricular apex,distal His bundle,and left bundle septal branch,respectively.After connecting a dual-chamber pacemaker,electrocardiographic and acute phase hemodynamic parameters under sinus rhythm,right ventricular apex pacing(RVAP),distal His bundle pacing(DHBP),and LBBP states were collected and analyzed.Three complete cardiac cycles of standard apical three-chamber color Doppler dynamic images were acquired under vector flow mapping(VFM)mode.Offline analysis was performed on obtained parameters including isovolumic contraction period,rapid ejection period,isovolumic relaxation period,rapid filling period,atrial contraction period,and left ventricular intracavitary energy consumption.These parameters were compared under pacing at different sites and the linear correlations of major parameters were analyzed.Results:The QRS duration of baseline intrinsic sinus rhythm,RVAP,DHBP and LBBP were(45.0±4.0)ms,(98.4±6.2)ms,(50.0±4.5)ms and(62.0±4.7)ms,respectively.The LBBP-QRS duration was significantly wider than intrinsic sinus rhythm and DHBP,but significantly narrower than RVAP(all P<0.01).Compared with baseline AOO mode(the pacing rate was performed at 10 beats/min above the intrinsic heart rate),the change of acute phase maximum left ventricular pressure rise rate(LVdP/dtmax)in RVAP,DHBP and LBBP was([-7.89±5.67]% ),([0.74±2.05]% )and([-0.14±3.59]% ),respectively.There was no significant difference in LVdP/dtmax changes between DHBP and LBBP(P=0.667),but both pacing modalities were significantly better than RVAP(all P<0.01).The average energy consumption of the left ventricle under RVAP was significantly higher than that of intrinsic sinus rhythm,DHBP,and LBBP in isovolumic contraction period,rapid ejection period,isovolumic relaxation period,rapid filling period,and atrial contraction period(all P<0.01).However,there was no statistically significant difference in energy consumption among intrinsic sinus rhythm,DHBP,and LBBP during the above five phases(all P>0.05).DHBP and LBBP did not show a significant increase in the number of left ventricular vortices,vortex area,and circulation intensity compared to intrinsic sinus rhythm,and LBBP did not show a significant increase in vortex area and circulation intensity compared to DHBP.Conclusions:Although LBBP canines significantly prolonged the paced QRS duration,it showed no significant differences in acute phase left ventricular hemodynamics,left ventricular flow field status,and energy consumption compared to intrinsic sinus rhythm and DHBP.Performance of LBBP was superior to RVAP.This study may contribute to revealing the theoretical basis of LBBP as a feasible physiological pacing therapy.

Objective In cases and events of mixed STR typing of aborted fetus,two methods for calculating paternity index(PI)of suspected biological fathers are proposed,which could be useful for theoretical reference for parental identification including mixed STR typing.Methods Depending on whether the fetal genotypes can be identified,the simple PI calculation method and the PI calculation method of deduced biological paternal genes when the fetal genotypes cannot be identified are proposed.Results The simple PI calculation method is to indentify the fetal genotypes first and then calculate according to the standard triplet.The PI calculation method of deduced biological paternal genes is to deduce all the possible genotypes of biological fathers conforming to Mendel's law(inference)without considering the ratio of peak height and peak area in mixed typing,and then calculate the parental index separately,taking the minimum value as the parental index of the locus.Conclusion When mixture ratio of fetus in the mixed typing of aborted tissue MR≥0.43,the accuracy of separation is very high and the simple PI calculation method can be accurate,so it is recommended.If 0.05≤MR＜0.43,it is suggested to use the calculation method of deduced biological paternal genes,which can avoid misjudgment of irrelevant persons to the greatest extent.If MR＜0.05,there's a high risk of fetal allele loss,we should not perform a paternity test on the mixed spot.Since the cumulative parental index calculated by deduced the biological paternal genes is usually lower than the value calculated by dividing the fetal genotype,the CPI may be lower than 10 000 when fewer loci are identified,and then more genetic markers should be detected.

Objective: To construct a novel carrier with core-shell structure-inner core of pFGF2-EGFP-loaded TACS coated by hydroxybutyl chitosan (HBC), and to explore its effects on granular fat graft survival. Methods: The core-structured particles (TACS-pFGF2-EGFP) and core-shell-structured particles (HBC@ TACS-pFGF2-EGFP) were prepared to explore the release pattern of pFGF2-EGFP of these particles. The expression of FGF2 protein was detected by Western-Blot in 293T cells transfected with the sustained - release microspheres in vitro. Cell proliferation assay demonstrated that 10μg/ml pFGF2 plasmid could promote 293T cells growth. Eighteen New Zealand white rabbits were used for adipose tissue transplantation experiment. Rabbit left ear was treated as experimental group, 2 ml fat granules and HBC@TACS-pFGF2-EGFP were implanted; rabbit right ear was used as control group, 2 ml fat granules and HBC@TACS-empty plasmids were transplanted. The specimens were harvested at 4, 8, 12 weeks separately after fat transplantation. Gross view, HE staining, and immunohistochemical staining were performed to observe graft survival, biological characteristics, and neovascular density. Results: HBC@TACS-pFGF2-EGFP particles could sustained release Pfgf2 gene in vitro, and successfully express FGF2 protein after transfecting 293T cells. At different time points after transplantation, the volume of adipose tissues was gradually reduced with time. The fat volume and survival rate of adipose tissues in the experimental group were significantly higher than that in the control group (P<0.05). HE staining showed that the arrangement of new adipocytes in the experimental group was more regular than that in the control group. Immunohistochemistry staining showed that the micro vessel density and FGF2 protein expression level in the adipose tissue of the experimental group were higher than those in the control group (P< 0.05). Conclusions HBC@TACS-pFGF2-EGFP particles with sustained release of FGF2 can improve the survival of granule fat transplantation.