Objective To analyze the dose‐effects of different doses of dexmedetomidine for sedation and sleep of the patients under epidural nerve block anesthesia .Methods A total of 82 patients undergoing elective lower limbs surgery(ASA grade Ⅰ - Ⅱ) were randomly divided into 4 different doses of dexmedetomidine groups(group 1 ,n=19 ;group 2 ,n=22 ;group 3 ,n=20;group 4 , n=21) ,under continuous epidural nerve block ,the loading dose of dexmedetomidine 0 .7 ,0 .8 ,0 .9 ,1 .0μg · kg -1 · h-1 was intrave‐nously pumped for 30 min ,then pumped at a rate of 0 .7 ,0 .8 ,0 .9 ,1 .0 μg · kg -1 · h-1 in the group 1 ,2 ,3 and 4 respectively .If any patient in 4 groups fell asleep at less than half an hour ,the loading dose was stopped and the continuous dose was changed to pump , the drug administration was discontinued at wound dressing after operation .Whether the patient falling asleep was recorded ,and the mean arterial blood pressure ,heart rate at 4 time points of 10 ,30 ,60 ,90 min after infusion of dexmedetomidine were also recorded . The 50% effective dose(ED50 ) ,ED95 and 95% confidence interval(CI) were calculated by using the Probit method .Results ED50 and ED95 of dexmedetomidine were 0 .65μg/kg(95% CI:0 .36-0 .73μg/kg)and 1 .00 μg /kg(95% CI:0 .90-1 .74μg/kg) ,which could decrease the heart rate and increase the arterial blood pressure .Conclusion Although dexmedetomidine can decrease the heart rate and increase the arterial blood pressure ,but the patients quietly fall asleep without discomfort and pain occurrence by the intra‐venous administration under continuous epidural nerve block .

BACKGROUND:In 1990s,overseas researchers use balloon occlusion method for establishing closed-chest animal models of myocardial infarction. But,ventricular fibrillation and thrombosis of intraoperative factors reduce the success rate of establishing the models. Currently,there are a few reports on establishing the large animal models. OBJECTIVE:We used balloon occlusion method for establishing closed-chest swine models of myocardial infarction,and explored ways to improve the success rate of modeling. DESIGN,TIME AND SETTING:The randomized controlled animal study of pathology observation was performed at the Department of Cardiology,First Affiliated Hospital of Kunming Medical College and Research Room of Pathology,Kunming Medical College from July 2008 to May 2009. MATERIALS:Fifteen Diannan small-ear pigs weighing 19-25 kg,aged 8-11 months,were divided into three groups:sham operation group,ischemia-reperfusion group,and ischemic postconditioning group,with 5 pigs in each group.METHODS:After the coronary occlusion and reperfusion period,the prophylactic use of lidocaine (1.0-2.0 mg/kg) infusion to control arrhythmia,and use of heparin to prevent and treat the thrombosis. A balloon catheter was positioned in the distal end of the first diagonal branch of the left anterior descending (LAD) artery under fluoroscopic guidance. In the sham operation group,the balloon was only placed to the LAD,did not block coronary artery. In the ischemia-reperfusion group,inflatable balloon occlusion was done for 60 minutes in the LAD after the balloon removed. In ischemic postconditioning group,after the balloon was inflated and occluded the LAD for 60 minutes,ischemic postconditioning was elicited by eight cycles of 30-second reperfusion,followed by 30-second reocclusion.MAIN OUTCOME MEASURES:Coronary angiography,electrocardiogram (ECG) and cardiac enzymes test was conducted to evaluate models of myocardial infarction. After three days,cardiac 2,3,5-triphenyltetrazolium chloride (TTC) staining and pathological examination was done to verily myocardial infarction.RESULTS:In the sham operation group,all pigs survived. In the ischemia-reperfusion group,4 pig models of myocardial infarction were successfully established,and one died of refractory ventricular fibrillation. In the ischemic postconditioning group,models of myocardial infarction after ischemia were successfully established. Following distal left anterior descending artery occlusion,the ECG leads V13 on the ST-segment elevation,the sick rational Q-wave formed;myocardial enzyme evolution of myocardial infarction in the human body was basically the same process. The site of myocardial infarction,basically the same parts,was located in apical,left ventricular anterior wall,and the former interval. TTC staining was normal myocardium brick red,myocardial infarct area appeared pale;pathological examination revealed a normal structure of myocardial infarct damage,cytoplasm condensed,dyeing deepening,transverse striations disappeared,nuclear enrichment,dissolution,fragmentation,many erythrocytes around the infarct area with abundant granulation tissue and a large infiltration of inflammatory cells.CONCLUSION:The described model presents a less invasion to the animals,and is the closest to the process of clinical practice.Intraoperative use of lidocaine and heparin for controlling arrhythmia and thrombosis of the models is successfully established as an effective manner. Ischemic postconditioning may be one of the factors for improving the modeling success rate.

BACKGROUND: Recent trials and clinical studies have shown that intracoronary transplantation of bone marrow-derived mesenchymal stem cells (MSCs) improves cardiac function following acute myocardial infarction (AMI). However, whether homing of MSCs into the infarcted myocardium or not is still unknown.OBJECTIVE: To study the homing of MSCs intracoronary administration in porcine myocardial infarction model using in vivo magnetic resonance imaging tracking.METHODS: Porcine MSCs were isolated and cultured by the whole bone marrow method. Following labeling by superparamagnetic iron oxide (SPIO), MSCs were treated with trypsinization to adjust the concentration at 10~(10)/L. Myocardial infarction was induced in all 10 pigs. At one week after modeling, the labeled MSCs were delivered via intracoronary infusion with standard over-the-wire (OTW) balloon angioplasty catheters. Prussian blue staining was used to evaluate labeling efficiency, and double echo steady state was used to scan four-chamber and cor biloculare at long axis view, which was considered as locating phase to obtain image of left ventricle at short axis view. RESULTS AND CONCLUSION: MSCs could be efficiently and safely labeled with SPIO. Intracoronary transplantation of MSCs is able to home the sites of myocardial injury and the border between infarcted and normal tissue. MRI can track SPIO-labeled MSCs delivered through intracoronary and were confirmed on pathology. After 5 weeks the injected labeled cells could still be detected with MRI.