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 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 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 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.

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.

OBJECTIVETo study the effect of excessive fluoride on calcium overload and apoptosis in cultured rat ameloblasts in vitro.

METHODSLogarithmic-phase ameloblasts (HAT-7) were treated with 0, 0.4, 0.8, 1.6, 3.2, and 6.4 mmol · L(-1) sodium fluoride (NaF) solution. Cell activities were detected by using a Cell Counting Kit 8 (CCK-8) assay after 48 h of treatment. The effect of fluoride on cell apoptosis was analyzed by using flow cytometry. Excessive fluoride-induced calcium concentration and calreticulin expression changes in ameloblasts were detected by using laser scanning confocal microscopy, Western blot analysis, and real-time quantitative polymerase chain reaction.

RESULTSNaF inhibited ameloblast activity at 1.6, 3.2, and 6.4 mmol · L(-1) (dose-dependent) after 48 h of induction. The Ca2+ fluorescence intensity of HAT-7 cells incubated with 1.6 and 3.2 mmol · L(-1) NaF was higher than that in the control group. The fluoride-induced early-stage apoptosis of ameloblasts after 48 h of induction and the early-stage apoptosis rate was positively correlated with fluoride concentration. Calreticulin mRNA expression in HAT-7 cells was higher than that in the control group after 48 h of incubation with 0.8, 1.2, and 1.6 mmol · L(-1) NaF.

CONCLUSIONExcessive fluoride-induced calcium overload in ameloblasts and further caused endoplasmic reticulum stress-mediated apoptosis.

Objective To evaluate efficacy of rotigaptide ZP123 on prevention of negative chronotropic effect caused by dexmedetomidine lengthening repolarization duration of the isolated rat hearts.Methods Eighteen healthy adult SD rats of either gender,weighing (300±30) g,were prepared isolated heart perfusion model by Langendorff.After 15 min perfusion and balance of K-H fluid,the isolated hearts were randomly divided into 3 groups (n=6 each): The hearts were continuously pefused for 30 min with 37℃ K-H solution in control group (group C),with dexmedetomidine 50 ng/ml in dexmedetomidine group (group D),or with rotigaptide 80 nmol/L combined with dexmedetomidine 50 ng/ml in rotigaptide combined with dexmedetomidine group (group ZD).In the whole Langendorff-perfused hearts,at the end of balanced infusion for 15 min (T0) and at 15(T1),30(T2) min of continued perfusion with K-H solution,the monophasic action potential (MAP) and heart rate (HR) were recorded from left anterior free wall,MAP duration at 50% repolarization (MAPD50) and at 90% repolarization (MAPD90),monophasic action potential amplitude (MAPA) and maximal velocity (Vmax) were calculated.Results Compared with T0,HR in group D was significantly declined at T1,T2;MAPD90 and MAPD50 in group D were significantly increased at T1,T2 (P<0.05).Compared with groups C and ZD,HR in group D was significantly declined at T1,T2;MAPD90 and MAPD50 in group D were significantly increased at T1,T2 (P<0.05).There was no significant difference in MAPA and Vmax between the three groups.Conclusion Rotigaptide antagonizes negative chronotropic effect induced by dexmedetomidine through shortening monophasic action potential duration in the myocardium of left ventricle of the isolated rat hearts.

Objective To investigate the effect of dexmedetomidine on myocardial repolarization heterogeneity and the expression of Cx43 during ischemia-reperfusion and the role of Cx43 in the dexmedetomidine for inhibition of myocardial repolarization heterogeneity during ischemia-reperfusion in isolated rabbit hearts.Methods Eighteen healthy adult rabbits,weighing (2.0±0.5) kg,were randomly divided into three groups after Langendorff isolated heart perfusion model had been prepared and K-H fluid had been perfused and balanced 15 min.In the control group (group C),37℃ K-H fluid was continuously perfused and balanced for 150 min.In group IR,K-H fluid was stopped after perfusion continue filling for 15 min,and then made the cardiac stop for 60 min with the injection of Thomas solution 10 ml/kg while the heart was protected by the 4℃ Thomas solution around.Following the reperfusion of 4℃ Thomas solution 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 given (group DEX),dexmedetomidine was added in the K-H fluid and the Thomas solution 25 ng/ml.The other procedures were the same as those of group IR.The heart rate (HR),90% monophasic action potential duration (MAPD90) were recorded at the time of balance perfusion record 15 min (T0),continue perfusion 15 min/balance 30 min (T1),reperfusion 30 min/balance 120 min (T2) and reperfusion 60min/balance 150 min (T3).The transmural dispersion of repolarization (TDR) was calculated.To observe the cardiac reperfusion arrhythmia and rebeating time and recording.Detection expression of Cx43 in the left ventricular myocardial by Western blot and immunohistochemistry at T3.Results Group DEX cardiac resuscitation time was significantly shorter than that of group IR (P<0.05).In group DEX.Compared with T0,HR was significantly decreased and TDR was significantly increased in groups IR and DEX at T2、T3 (P<0.05).Compared with group IR,the TDR of group DEX was significantly decreased at T2、T3 (P<0.05).Compared with group C,the expression of Cx43 was decreased (P<0.05) and the distribution was not uniform in groups IR and DEX.Compared with group IR,the expression of Cx43 was decreased (P<0.05) and the distribution was improved in group DEX.Conclusion Dexmedetomidine could inhibits myocardial repolarization heterogeneity of ischemia-reperfusion injury,and thus play a stable cardiac conduction,reduce reperfusion arrhythmias,and its mechanism may be that dexmedetomidine could inhibits gap junctional uncoupling and inhibits expression and distribution of connexins decreased.