AIM: To study the effect of changing left ventricular afterload and isolated perfused rabbit heart on ventricular refractory period measured by subhthreshold conditioning train stimulation (St).METHODS:Ventricu- lar refractory pened strength- interval relation was measured by St method under the condition of changine left ven- tricular afterload and elimination action of nervous and body fluid.RESULTS: Reducing left ventricular afterload pro -longed ventricular refractory period measured by St method (P

BACKGROUND:Autologous stem celltransplantation to the heart is a research direction of heart failure treatment, but there are relatively few of studies about autologous bone marrow mesenchymal stem celltransplantation targeting the cardiac conduction system. OBJECTIVE:To evaluate the potential of rabbit bone marrow mesenchymal stem cells for treatment of heart block. METHODS:Rabbit bone marrow mesenchymal stem cells were induced by 5-azacytidine to differentiate into cardiomyocyte-like cells. After thoracotomy, the left atrium-left ventricular anterior wal was sutured in 14 New Zealand white rabbits (8 in the experimental group and 6 in the control group). One month after the surgery, in the experimental group, autologous bone marrow mesenchymal stem cells induced by 5-azacytidine for 4 weeks were labeled with 4',6-diamidino-2-phenylindole and then injected into the suture area when opening the thoracic again. In the control group, cells cultured in medium were used. One month after celltransplantation, the third thoracotomy was done to insert electrodes into the left atrium and left ventricular anterior wal , for cardiac electrophysiological detection. Whether atrioventricular pathway formed in the suture area was observed. RESULTS AND CONCLUSION:After cells were transplanted into the sutured area, two rabbits in the experimental group were discovered to form the atrioventricular pathway in the sutured area through cardiac electrophysiological examination. After transplantation, transplanted cells were visible on the heart frozen sections under fluorescence microscope in the left ventricle and sutured area, but there was no cellin the control group. In the experimental group, bone marrow mesenchymal stem cells expressed Cx43 and formed gap junction intercellular communication with cardiomyocytes, which was presented as formation of the atrioventricular pathway on cardiac electrophysiology examination. These findings indicate that bone marrow mesenchymal stem cells can be used to treat cardiac conduction system block diseases.

Aim To observe the effects of Rh2 on the hemodynamics and electrophysiological parameters in anesthetic rats. Methods The changes of hemodynamics and electrophysiological parameters in anesthetic rats were tested after administration with Rh2, such as SAP, DAP, MAP, LVSP, LVDP, LVEDP, ?dp/dt_ max,HR,RRP and ERP. Results Rh2 increased SAP,DAP,MAP,LVSP,?dp/dt_ max with the decrease of LVEDP. It had no distinct effects on HR, ECG, RRP and ERP. Conclusion Rh2 has the effects of increasing SAP,DAP and MAP in anesthetic rats and has no influence on HR, ECG and cardiac ventricle electrophysiological parameter, suggesting that the effect of increasing blood pressure could be related to the increases of peripheral resistance.

AIM:To study the effects of changing right heart load on electrophysiologic parameters in anesthetized dogs. METHODS:Change of right atrial and ventricular load, right atrial and ventricular diastolic threshold (ADT, VDT), right atrial and ventricular relative refractory period (ARRP,VRRP) and right atrial and ventricular effective refractory period (AERP, VERP) were recorded. RESULTS: Increasing right heart load step by step(grade A and B) caused prolongation of ARRP, AERP, VRRP (grade B, P

Objective:To study the morphologic standard values of craniofacial hard-tissue of the youths in Xi'an.Methods:CBCT scanned cephalometric data of 100 selected volunteers (50 males and 50 females)with individual normal occlusion were collected.31 landmarks and 31 measurements were compared between sexes and between 3D and 2D data with software InvivoDental 5.2,WinCeph 8.0.and SPSS 19.0.Results:1.In the 3D measurements,vertical growth of mandible in the females was more than that in the males. The values of torque of lower incisor,basis length,height of rumi mandibulae and length of corpora mandibulae in the males were bigger than those in the females.2.Compared with 2D measurements,there existed statistically significant differences in most parameters except U1-NA(mm).Conclusion:3D analysis with CBCT may provide more accurite morphologic data for craniofacial hard tissues.