Objective To evaluate the effects of different concentrations of remifentanil on the expression and distribution of gap junction protein connexin 43 (Cx43) in the cardiomyocytes of rabbits.Methods Healthy adult rabbits of both sexes,weighing 2.0-2.5 kg,were anesthetized with pentobarbital sodium.Their hearts were rapidly excised and retrogradely perfused in a Langendorff apparatus with K-H solution saturated with 95％ O2-5％ CO2 at 37 ℃.After 15 min of stabilization with K-H solution,the 24 isolated hearts were randomly divided into 4 groups (n =6 each) using a random number table:control group (group C),and low,medium and high concentrations of remifentanil groups (R1-3 groups).The hearts were continuously perfused with K-H solution at 37 ℃ in group C.The hearts were perfused for 60 min with K-H solution containing remifentanil 12,25 and 50 ng/ml in R1-3 groups,respectively.The myocardial specimens were then obtained from the anterior wall of the left ventricle for detection of the expression and distribution of Cx43 by Western blot and immunohistochemistry,respectively.Results The expression of Cx43 was gradually down-regulated in C and R1-3 groups in turn (P＜0.05).Compared with group C,there was a tendency for the proteins localized at end-to-end contact sites of ventricular cardiomyocytes to localize at side-to-side contact sites in R1-3 groups,and the distribution was messy in R1-3 groups.Conclusion Remifentanil dose-dependently down-regulates the expression of Cx43 and changes the distribution of Cx43,which may be one of the mechanisms of remifentanil-induced arrhythmia in rabbits.

AIM:To study the effect of remifentanil on monophasic action potential and transmural dispersion of repolarization (TDR) in the 3-layer myocardium of isolated rabbit hearts .METHODS:Adult rabbits (n=18, 2.0 ~2.5 kg) were used to isolate the hearts for preparing Langendorff perfusion model .The hearts were randomly divided into 3 groups after perfusion with K-H solution for 15 min: the perfusion in control group ( C group ) continued for 60 min; the hearts in remifentanil group ( R group ) were perfused with 12 μg/L remifentanil K-H solution for 60 min; the hearts in remifentanil+aminophylline group ( RA group ) were given 60-min perfusion of 12 μg/L K-H remifentanil +30 mg/L aminophylline .The HR and 3 layers of myocardial monophasic action potential ( MAP) in the left ventricular anterior wall were recorded at time points after balanced infusion for 15 min ( T0 ) , and continued perfusion for 15 min ( T1 ) , 30 min ( T2 ) and 60 min ( T3 ) .The monophasic action potential duration of repolarization at 90%( MAPD90 ) and the transmural dispersion of repolarization (TDR) were calculated.The early afterdepolarization, delay afterdepolarization and arrhythmia were also observed.RESULTS:In R group, slower HR and prolonger MAPD90 and TDR at T1 ~T3 were observed as com-pared with those at T0(P<0.05).R group showed slower HR and longer MAPD 90 and TDR than C group and RA group (P<0.05).CONCLUSION:Remifentanil slows the HR, extends the MAPD90 and increases the TDR, thus being prone to induce reentry.Aminophylline makes HR faster and MAPD90 shorter, thereby reducing the TDR.

Objective To analyze the occurrence and clinical features of chronic kidney disease (CKD) in the ICU patients and identify the possible risk factors.Methods A retrospective study was performed in 2281 ICU patients enrolled from Shengjing hospital between January 2007 and December 2010,in which 1860 cases had complete data and were followed-up,the other 421 cases were excluded for the reasons of dying,suffering from CKD originally,lacking complete data and missing.The cases were divided into CKD and non-CKD groups according to SCODRED and CKD diagnosis standards.Assessment was performed to screen risk factors of CKD.Results There were obvious differences between CKD and non-CKD groups at age,pregnancy,AKI and liver function (P ＜0.05).The CKD's annual morbidity rate of ICU patients was 20％-30％,and the incidence showed an increasing trend with time.Age,pregnancy,AKI,APACHE-Ⅱ score,invasive diagnosis and treatment,mechanical ventilation,organ failure and kidney-hurt drugs were risk factors for CKD in the ICU patients.Conclusions The morbidity rate of CKD in the ICU patients is high,and the number of CKD patients show an increasing trend with time.Age,APACHE-Ⅱ score ＞ 15,the number of failed organs ≥2,the variety of kidney-hurt drug≥2,pregnancy,AKI,the number of invasive diagnosis and treatment≥3,mechanical ventilation are independent risk factors of CKD in the ICU patients.

Objective To characterize angular dependency of MatfiXX and develop a method for its calibration in order to verify treatment plan with original gantry angles.Methods Absolute dose calibration was carried with thimble ionization chamber on the linear accelerator.so as to make sure 1 MU=1 cGy at the depth of maximum dose(dmax).A MatriXX was put into a Mutlicube phantom,and the ionization chamber matrix was calibrated with absolute dose.In order to determine a correction factor CF as a function of gantry angle θ.open beam fields of 10 cm×10 cm size were irradiated for gantry angles θ=0°-180°(every 5°)and every 1°for lateral angles θ in the range of 85°-95°.CF was defined as the ratio of the dose measured with ionization chamber and the dose from MatriXX.Results Relatively large discrepancies in response to posterior VS.anterior fields for MatriXX detectors(up to 10%)were found during the experiment and relatively large variability of response as a function of gantry angle.The pass rate of treatment plan in lateral beams was lower than that of other beams.The isodose distribution of corrected MatriXX matched well with the outcome from the treatment planning system. Conclusions The angular dose dependency of MatriXX must be considered when it is used to verify the treatment plan with original gantry angles.

Objective To evaluate the efficacy of minimally invasive percutaneous intervertebral disc approach for treatment of sympathetic cervical spondylosis. Methods Fifty?six patients diagnosed as having sympathetic cervical spondylosis from January 2009 to August 2014, aged 22-64 yr, with the dis?ease course ranged from 6 months to 15 yr and a follow?up period of 6 months, were enrolled in the study. The related minimally invasive approach was selected according to the height of the diseased intervertebral space. When the ratio of the height of diseased intervertebral space∕normal intervertebral space≤1∕3, per?cutaneous radiofrequency ablation was used ( groupⅠ, n=19); when the ratio within the range of 1∕3-2∕3, percutaneous laser disk decompression was used ( groupⅡ, n=12); when the ratio≥2∕3, low?tem?perature plasma radiofrequency ablation was used ( group Ⅲ, n=25) . Before operation, at 2 weeks after operation, and at 1, 3 and 6 months after operation, the sympathetic symptoms were evaluated using the 20?point score. At 2 weeks and 6 months after operation, the patients′ subjective satisfaction was assessed and graded ( excellent, good, medium and poor ) . Results All the patients were followed up for 6 months. The sympathetic symptom scores were significantly lower at each time point after operation in Ⅰand Ⅲ groups and at 2 weeks and 3 and 6 months after operation in group Ⅱ than those before operation
( P<0.05) . The excellent and good rate of patients′subjective satisfaction was 67.9% at 2 weeks after op?eration, and 76.8% in the last follow?up period at 6 months after operation. Conclusion The minimally invasive percutaneous intervertebral disc approach has a marked short?term effect on sympathetic cervical spondylosis.

Objective To evaluate the effects of different concentrations of remifentanil on myocardial monophasic action potential (MAP) in isolated rabbit hearts.Methods Adult rabbits of both sexes,weighing 2.0-2.5 kg,were used in the study.Their hearts were excised,and retrogradely perfused with oxygenated K-H solution saturated with 95％O2-5％CO2 at 37 ℃ in a Langendorff apparatus.Twenty-four isolated hearts were randomly divided into 4 groups (n =6 each) using a random number table:control group (group C) and 3 different concentrations of remifentanil groups (group R1-3).After 15 min of stabilization,K-H solution was continuously perfused for 60 min in group C,and K-H solution containing 12,25 and 50 ng/ml remifentanil was continuously perfused for 60 min in R1,R2 and R3 groups,respectively.At 15 min of stabilization,and 15,30 and 60 min of perfusion with K-H solution,the heart rate,and the maximal velocity and amplitude of the MAP in the three layers of the left ventricular anterior wall were recorded,and the action potential duration at 90％ repolarization and transmural dispersion of repolarization (TDR) were calculated.Results Compared with group C,the heart rate was significantly decreased,and the action potential duration at 90％ repolarization and TDR were significantly prolonged at 15,30 and 60 min of perfusion in R1-3 groups (P＜0.05).Compared with C and R1 groups,the maximal velocity and amplitude of MAP were significantly decreased at 15,30 and 60 min of perfusion in R2 and R3 groups (P＜0.05).Conclusion Low-concentration remifentanil induces heart block through increasing TDR,however,high-concentration remifentanil induces heart block through inhibiting myocardial MAP depolarization and increasing TDR in the isolated rabbit hearts.

Objective To investigate the changes in volume and spatial location of target areas and normal tissues before and during intensity?modulated radiotherapy (IMRT) for cervical cancer by quantitative means. Methods Forty patients with cervical cancer who were treated with IMRT were enrolled as subjects. Computed tomography ( CT) was performed before IMRT and during IMRT when a dose of 27 Gy ( 15 fractions) was reached. Clinicians delineated the target areas and organs at risk in the two groups of CT images. The target areas and organs at risk in one group of images were mapped to the other group of CT image by image registration using the Pinnacle treatment planning system. Volume changes in target areas and organs at risk were analyzed, and changes in the spatial location were evaluated by volume difference method and Dice similarity method. Comparison was made by paired t?test. Results There were significant differences in gross target volumes of primary tumor lesions ( GTV?T) and pelvic metastatic lymph nodes (GTV?N) before and during IMRT ( P= 0?? 000; P= 0?? 000). According to the evaluation by volume difference method, the average rate of change in GTV?T was (38.64±19?? 50)% with a range between 3?? 16%and 86?? 49%, while the average rate of change in GTV?N was (42.49± 25?? 68)% with a range between 2?? 79% and 87?? 42%. In the organs at risk, the bladder had the maximum rate of volume change, the average of which was (55.13±33?? 40)% with a range between 3?? 25% and 116?? 01%. According to the evaluation by Dice similarity method, the average Dice similarity coefficient for GTV?T was 0.50± 0?? 18 with a range between 0?? 10 and 0?? 85, while the average Dice similarity coefficient for GTV?N was 0.31±0?? 20 with a range between 0?? 00 and 0?? 71. The rectum had the minimum Dice coefficient in the organs at risk, the average of which was 0.57± 0?? 14 with a range between 0?? 18 and 0?? 76 . Conclusions For patients with cervical cancer to receive IMRT, since there are substantial changes in volume and spatial location of target areas and normal tissues before and during treatment, it is quite necessary to modify the treatment regimen in time in order to provide adequate doses for target areas and avoid overdose for organs at risk.

Objective To investigate the effects of target-controlled confusion of propofol with different concentrations on ventricular repolarization after prophylactic infusion of cefuroxime sodium. Methods Sixty ASA physical status Ⅰ or Ⅱ female patients,aged 18-65 years,undergoing elective gynecological surgery were randomly divided into three groups:group P2 (n =20)with TCI 2 μg/ml, group P3 (n =1 9)with TCI 3 μg/ml and group P4 (n =20)with TCI 4 μg/ml.Firstly,they were re-hydrated;secondly,the patients in groups P2,P3 and P4 were intravenous infused with cefuroxime sodium 2.5 g (in 100 ml normal saline)and then target-controlled infused of propofol 2 μg/ml,3μg/ml and 4 μg/ml in target plasma concentration,respectively.At three pionts of time:after rehy-dration before intravenous antibiotics (T0 ),after intravenous antibiotics before TCI of propofol (T1 ), after TCI of propofol (T2 ),QT interval,QTc interval,Tp-e interval were measured and recorded, respectively.Results Compared with T0 ,QTc [(469.9 ± 34.0)ms vs.(451.2 ± 24.9)ms],Tp-e [(107±25)ms vs.(94±20)ms]and Tp-e/QT (0.260±0.058 vs.0.236±0.043)in group P4 were sig-nificantly prolonged at T1 (P < 0.05 ).Compared with T1 ,QTc of groups P2 [(437.4 ± 24.4)ms vs. (453.3±28.0)ms]and P4 [(438.8±29.9)ms vs.(469.9±34.0)ms]were shortened significantly at T2 (P <0.05).Conclusion Propofol could improve ventricular reporlarization heterogeneity caused by cefu-roxime sodium.

Objective To investigate the role of potassium channel in remifentanil-induced prolongation of monophasic action potential duration (MAPD) in the myocardium of rabbits.Methods Eighteen adult rabbit hearts successfully perfused in a Langendorff apparatus were randomly divided into 3 groups (n =6 each) using a random number table:control group (group C),remifentanil group (group R),and K+ channel blocker tetraethylammonium group (group T).After 15 min stabilization with K-H solution,group C was continuously perfused with K-H solution for 60 min,and R and T groups were perfused with KH solution containing 12 ng/ml remifentanil and 10 ng/ml tetraethylammonium,respectively,for 60 min.At 15 min of stabilization,and 15,30 and 60 min of perfusion,heart rate,MAPD of all the three layers of the myocardium in the anterior wall of the left ventricular was recorded.MAPD at 50％ and 90％ repolarization (MAPD50,MAPD90) were calculated.Results Compared with group C,heart rate was significantly decreased,MAPD50 and MAPD90 were prolonged in R and T groups (P ＜0.05).Conclusion The mechanism by which remifentanil prolongs MAPD in the myocardium of rabbits is associated with blockade of the potassium channels.

Objective To study the effects of dexmedetomidine on the monophasic action po-tential duration and the transmural dispersion of repolarization during ischemia-reperfusion of isolated rabbit hearts and thus explore its effect on myocardial ischemia-reperfusion electrophysiological char-acteristics.Methods Eighteen healthy adult rabbits,weighing (2.0±0.5)kg,were randomly divided into 3 groups after successful preparation of Langendorff isolated heart perfusion model and 1 5 min perfusion and balance of K-H fluid.In the control group (group C),37 ℃ K-H fluid was continuously perfused and balanced for 1 50 min.In the ischemia/reperfusion group (group IR),K-H fluid was stopped after continuous perfusion and balance for 1 5 min and cardiac arrest was induced for 60 min with the injection of Thomas solution (4 ℃,10 ml/kg)while the heart was protected by the low tem-perature Thomas solution (4 ℃)around it.Reperfusion of Thomas solution (4 ℃,5 ml/kg)was performed for 30 min and the heart was resuscitated by the perfusion of K-H fluid for 60 min.In dexmedetomidine group (group DEX),dexmedetomidine (25 ng/ml)was added in the K-H fluid and the Thomas solution.Other procedures were same as in group IR.Heart rate(HR),monophasic ac-tion potential amplitude (MAPA)of the three layers of heart [endocardium (Endo),myocardium (Mid)and epicardium (Epi)],0 phase maximal increase rate (Vmax),90% monophasic action po-tential duration (MAPD90 )and transmural dispersion of repolarization (TDR)were recorded at the time of continuous balance perfusion 1 5 min(T0 ),continuous perfusion 1 5 min/balance 30 min(T1 ), reperfusion 30 min/balance 120 min(T2 )and reperfusion 60 min/balance 1 50 min(T3 ).Cardiac ar-rhythmia and resuscitation time at cardiac reperfusion were observed,without using drugs to restore normal cardiac rhythm.Results In group DEX,cardiac resuscitation time was significantly shorter (1 6.67±3.78)s than that in group IR (46.33±7.29)s (P <0.05);At T2 ,in group IR,arrhythmia was seen in 6 rabbits and normal cardiac rhythm was restored within 2 min in two rabbits,while in group DEX,arrhythmia was seen in 2 rabbits and normal cardiac rhythm was restored within 2 min in one rabbit,without the use of any drugs.When compared with T0 ,HR was slower at T2 and T3 in group IR and at T1-T3 in group DEX (P <0.05);Compared with T1 ,HR was slower at T2 and T3 in group DEX (P <0.05);Compared with T2 and group C,HR was slower at T3 in group DEX;At T1-T3 ,HR in group DEX were significantly slower than that in group IR (P <0.05).Compared with T0 ,MAPD90 of Mid at T1 and Epi,Mid,Endo at T2 and T3 in group DEX were significantly extend-ed (P <0.05);Compared with T1 ,MAPD90 of Epi,Mid,Endo in group DEX were significantly ex-tended at T3 ;MAPD90 of Mid in group DEX was significantly longer than that in group C at T3 (P <0.05);At T2 and T3 ,MAPD90 of Epi,Mid,Endo in group DEX were longer than that in group IR (P <0.05).Compared with T0 and group C,TDR at T2 and T3 in group IR and at T1-T3 in group DEX significantly increased (P <0.05),while TDR in group DEX were less than that in group IR at T2 and T3 (P <0.05).Conclusion Dexmedetomidine appeared to prolong MAPD and restrain the dis-proportion of resuscitation of myocardial ischemia-reperfusion injury.Dexmedetomidine could have the effect of stabilizing myocardial ischemia-reperfusion electrophysiological characteristics.