Changes of Monophasic Action Potential Duration and Effective Refractory Period of Three Layers Myocardium of Canine during Acute Ischemia in Vivo

Summary： The effect of acute ischemia on the electrophysiological characteristics of the three layers myocardium of canine in vivo was investigated. Twelve canines were divided into two groups randomly： acute ischemia （AI） group and sham operation （SO） group. By using the monophasic action potential （MAP） technique, MAP and effective refractory period （ERP） of the three layers myocardium were measured by specially designed plunge needle electrodes and the transmural dispersion of repolarization （TDR） and transmural dispersion of ERP （TDE） were analyzed. The results showed that in the AI group, MAP duration （MAPD） was shortened from 201.67±21.42 ms to 169.50±13.81 ms （P〈0.05）, but ERP prolonged to varying degrees and TDE increased during ischemia. In the SO group, MAPD and ERP did not change almost. Among of the three layers myocardium of canine, MAPD was coincident in two groups. It was concluded that during acute ischemia, MAPD was shortened sharply, but there was no significant difference among of the three layers myocardium. The prolonged ERP was concomitant with increased TDE during acute ischemia, which may play an important role in the occurrence of arrhythmias induced by acute ischemia. These findings may have important implications in arrhythmogenesis.

Effects of Electric Stimulations Applied during Absolute Refractory Period on Cardiac Function of Rabbits with Heart Failure

The effects of electric currents applied during absolute refractory period （ARP） on the cardiac function of rabbits with heart failure due to myocardial infarction （MI）, and the safety of this method were investigated. Thirty rabbits were randomly assigned equally to 3 groups： sham-operated group, LV-anterior wall cardiac contractility modulation （LV-CCM） group, and septum-CCM （S-CCM） group. A thoracotomy was performed on all the rabbits. Electric pulses were delivered during the ARP on the anterior wall of left ventricle in CCM group and in the septum in S-CCM group, respectively. The left ventricular systolic pressure （LVSP） and maximum positive left ventricular pressure change （＋dp/dtmax）, heart rates, ventricular tachycardia, ventricular fibrillation were observed. It was found that, as compared with the baseline, LVSP, and ＋dp/dtmax were significantly increased, on average, by 15.2% and 19.5% in LV-CCM group （P〈0,05）, and by 8.5% and 10.8% in S-CCM group （P〈0.05）. LVEDP was significantly decreased and -dp/dtmx increased both in LV-CCM group and S-CCM group （P〈0.05）. CCM had no effect on heart rate and induced no arrhythmia in short time. It is concluded that electric currents delivered during the ARP could significantly enhance the contractility of myocardium safely, suggesting that CCM stimulation is a novel potent method for contractility modulation.

Effects of Electric Stimulations Applied During Absolute Refractory Period on Ventricular Muscle from Rabbits

Objectives To investigate the influences of electric signals applied during absolute refractory period (ARP) on the contractility of isolated papillary muscle from rabbits. Methods Papillary muscle was exercised from the right ventricle and was paced at 1 Hz. Biphasic square wave current pulse was delivered during the absolute refractory period (called CCM) in isolated, superfused, isometrically contractility rabbit papillary muscle. The peak tension (PT) of papillary muscle, as well as maximum positive tension change ( + dT/dtmax), were observed. Results Compared with the baseline, both PT and + dT/dtmax significantly increased during CCM stimulation by 18.2% and 21.4% respectively (P < 0. 05) . In addition, PT increased significantly with one or two beats following CCM signal application and reached a. new steady state level after a few beats. Once the CCM signals were turned off, the PT returned to the approximately baseline level ( P < 0. 05). Moreover, the effect of CCM on PT was dose - response to voltage. The obvious effect was at higher voltage. No effect was observed at lower voltage. Conclusions Electric signals delivered during the absolute refractory period can rapidly enhance the contractility of myocardium, which suggests that CCM signal is a novel potent method for contractility modulation.

Effects of Amiodarone on Transmural Dispersion of Ventricular Effective Refractory Periods across Myocardial Layers in the Normal and Hypertrophic Canine Heart

The effects of amiodarone on transmural dispersion of ventricular effective refractory periods （ERPs） in the normal and hypertrophic canine heart were investigated in vivo. By using the programmed stimulation protocol, the ERPs of epicardium （Epi）, midmyocardium （Mid） and endocardium （Endo） were measured by inserting specially-designed electrodes into the three myocardial layers before and after mainlining of amiodarone. No significant ERPs-dispersion was observed in the three layers before and after mainlining of amiodarone in the normal group. In contrast, ERPs of all the three layers were prolonged in the hypertrophic heart, while the ERPs-dispersion was reduced significantly after mainlining of amiodarone. The ERPs-dispersion was significantly increased in the hypertrophic heart but not in the normal heart using ＂long-short＂ and ＂short-long＂ interval stimulation technique. It was concluded that （1） the differences in ERPs-dispersion among the three layers were significant in hypertrophic heart, and differences were not significant in normal canine heart; （2） ERPs of each three-myocardial layers were significantly prolonged after using amioda- rone, but the ERPs-dispersion decreased in hypertrophic heart and （3） the programmed extrastimulus technique of ＂long-short＂ and ＂short-long＂ intervals increased the transmural ERPs-dispersion in the hypertrophic heart.

Influence of Selective Edge Removal and Refractory Period in a Self-Organized Critical Neuron Model

A simple model for a set of integrate-and-fire neurons based on the weighted network is introduced. By considering the neurobiological phenomenon in brain development and the difference of the synaptic strength, we construct weighted networks develop with link additions and followed by selective edge removal. The network exhibits the small-world and scale-free properties with high network efficiency. The model displays an avalanche activity on a power-law distribution. We investigate the effect of selective edge removal and the neuron refractory period on the self-organized criticality of the system.

Effect of β_3-adrenoceptors on Ventricle Fibrillation Threshold and Effective Refractory Period in Rats With Heart Failure

Objectives To observe the effect of β3-Adrenoceptor （AR） on ventricle fibrillation threshold （VFT） and effective refractory period （ERP） in rats with heart failure. Methods Rats were randomized into control group and heart failure group. The expression of β3-ARmRNA was detected with RTPCR; The VFT, ERP, LVESP,LVEDP, ＋dp/dtmax and -dp/dtmax was measured at the same time with administration of BRL37344 （ 2 nmol / kg, β3- AR agonist）. Results ①Both the expression of β3-AR mRNA and the proportion increased in rats with heart failure in comparison with control rats （0.028 vs. 0.011 and 5.4% vs 1.2%, P 〈 0.05）;② ERP was longer in rats with heart failure than control group （70.5±5.5 ms vs 59.5±6.4ms, P 〈 0.05） and there was no difference of ERP in rats with heart failure with administration of BRL37344 （73.0±4.8 ms vs 70.5± 5.5 ms, P 〉0.05）; ③VFT was lower in rats with heart failure than control group（10.9±0.8 mv vs 30.5± 1.3 mv, P〈 0.05） and decreased obviously in rats with heart failure with administration of BRL37344 （7.1±0.6 mv vs 10.9±0.8 mv, P 〈 0.05） ; The decrease of VFT correlated with the effect on LVESP, ＋dp/ dtmax,-dp/dtmax of BRL37344 and the expression of β3-AR mRNA （correlation coefficient： 0.788, 0.708, 0.759, 0.787; P 〈 0.05）. Conclusions The expression of β3-AR mRNA of left ventricle was obviously increased in rats with heart failure, and activation of β3-AR had no effect on ERP but could decreased VFT which correlated with the effect of β3-AR on LVESP, ＋dp/dtmax, -dp/dtmax and the expression of β3-AR mRNA.

Effects of Electrical Stimulation During Absolute Refractory Period on Contraction and Relaxation of Cardiomyocytes from Normal Guinea - pigs

Objectives To investi-gate the effect of electrical stimulation during absolute refractory period on contraction and relaxation of ventricular myocytes from normal guinea - pigs. Methods The guinea - pig ventricular myocytes were obtained by enzyme digesting, and the extent of its contraction and relaxation and Ca2+ transient were recorded through the motion edge detection system. Results (1) The contracting extent of guinea - pig ventricular myocytes increased 15.45±6.48% , and the peak velocity of shorting (contraction) and the peak veloci ty of relengthening (relaxation) increased 15.97 ± 8.37% and 21. 63±8. 06% respectively (n = 10); (2) The extent of ventricular myocytes fluorescence ra tio(360/380) (F360/F380) increased 22. 55±9. 08%, and the peak velocity of ventricular myocytes F360 /F380 increased 36. 75 ± 9. 77% and 23. 62±4. 47% during shorting and relengthening respectively (n = 6) . Conclusions Appropriate electrical stimulation may strengthen the contracting and relaxing function of normal guinea - pig ventricular myocytes.

A Reevaluation of the Critical Membrane Potential of the Effective Refractory Period in Guinea Pig Ventricular Fibres

The traditional critical membrane potential (CMP), -55—-60mV, which corresponds to effective refractory period (ERP), was anew investigated in guinea pig ventricular muscle fibres. The electrical and contractile responses to the stimulus during repolarization of action potential (AP), particularly from+10 to -60 mV, were observed. One third of 35 tested cells displayed testing action potential (TAP) and local response at≥-54 mV when they were stimulated by testing pulses in 37℃ normal Tyrode's solution. Potential level of TAP which occurred earliest was at -30 mV and that of local response which appeared earliest was at 0 mV during repolarization among 95 systematic tests. Most of the TAPs belonged to the slow response potential type. The ratio of TAP evoked at ≥-54 mV initial membrane potential (IMP) was as high as 86% when the experiment was carried out in 37℃ 1.5 mmol KC1/L Tyrode's solution. In view of distribution of IMPs of TAPs, the CMP of ERP in guinea pig ventricular muscle fibres was more positive than traditional CMP measured by Hoffman et al. in dog, sheep Purkinje fibres and had a quite changeable range. The CMP of every cell in ventricular muscle was not all the same, and their CMPs approximated to normal distribution. There was no sharp line separating ERP from relative refractory period in myocardium. Higher temperature and low [K]_0 were the important factors elevating CMP of ERP.

Variation of repetitive cortical spreading depression waves is related with relative refractory period： a computational study

Cortical spreading depression （CSD） is an important experimental model for diseases such as stroke, epilepsy and migraine. Previous observations indicated that the amplitude and velocity of the typical direct current potential shift during repetitive CSD waves were varying. The recovery state of the tissue was found related with the variation of successive CSD waves. A computational model in this paper aimed to investigate the role of relative refractory period of CSD. This model simulated that continuous injection of KCI solution induced repetitive CSD waves. The first CSD wave often had a larger amplitude and faster velocity than those of the succeeding secondary waves. The relative refractory period lasted much longer than the recovery of ions turbulence. If the induction interval was long enough for recovery, a series of CSD waves would have the same profile asthe first one. In the relative refractory period, an early stimulation might lead to a late initiation of CSD, i.e., ＂haste makes waste＂. The amplitude and velocity of CSD waves were found increasing with the initiation interval and asymptotic to those of the first CSD wave. This study verified that the propagation dynamics of CSD waves is modulated by the relative refractory period. It suggested that the refractory period is critical for preventing undesirable CSD waves.

肝移植围手术期脑卒中的研究进展

肝移植是目前治疗终末期肝病的标准手段之一,随着手术技术的发展以及围手术期管理的优化,肝移植术后并发症的发生率有所下降,但围手术期神经系统并发症仍较为常见,其中脑卒中的发生率差异较大,病因复杂多样,且起病隐匿、进展迅速、病死率高。对肝移植围手术期脑卒中进行早期识别及诊断,及时进行有效治疗,对于改善患者预后具有重要意义。因此,本文就肝移植围手术期脑卒中的概念、发生情况、危险因素、诊断、治疗及预防进行综述,探讨肝移植围手术期脑卒中的研究进展,以期为肝移植围手术期脑卒中的诊治提供参考。

不同时期RMPP患儿支气管肺泡灌洗液SPA表达及与肺功能的关系

目的探讨不同时期难治性支原体肺炎(refractory mycoplasma pneumoniae pneumonia,RMPP)患儿支气管肺泡灌洗液中表面活性物质相关蛋白-A(surfactant protein A,SPA)的表达水平及与肺功能的关系。方法选取2021年1月—2023年1月南通市第一人民医院收治的62例RMPP患儿为对象,以同期行支气管镜异物取出术且无肺部感染的50例患儿为对照组。RMPP患儿于急性期、恢复期行支气管肺泡灌洗液中SPA检测以及肺功能指标检测[第1秒用力呼气容积(forced expiratory volume in one second,FEV_(1))、用力肺活量(forced vital capacity,FVC)、FEV_(1)/FVC],对照组同样如此。比较三者检测结果差异,使用Pearson分析RMPP患儿支气管肺泡灌洗液中SPA水平与肺功能指标的相关性。结果RMPP患儿肺泡灌洗液中的SPA急性期(59.82±12.64)μg/L、恢复期(129.91±24.86)μg/L高于对照组,差异有统计学意义(P<0.05)。RMPP急性期、RMPP恢复期的FEV_(1)、FVC、FEV_(1)/FVC(80.95±6.88)%、(88.41±5.75)%较对照组低,差异有统计学意义(P<0.05);RMPP患儿于急性期时肺泡灌洗液中的SPA较恢复期低,FEV_(1)、FVC、FEV_(1)/FVC较恢复期低,差异有统计学意义(P<0.05);RMPP患儿肺泡灌洗液中SPA水平与FEV_(1)、FVC、FEV_(1)/FVC呈正相关(P<0.05)。结论RMPP患儿病情处于急性发展阶段的情况下其支气管肺泡灌洗液中的SPA表达相较病情恢复阶段更低,同时RMPP患儿支气管肺泡灌洗液中SPA水平与其肺功能指标呈正相关性。

难治性癫痫的外科治疗进展

在癫痫患者中,药物难治性癫痫一直占据相当比例。这部分患者在经过精确的评估后或可通过外科治疗的手段达到发作缓解。本文阐述了难治性癫痫的术前神经电生理和影像评估方法,并结合最新临床研究进展,针对不同类型癫痫总结手术治疗方案,补充阐述了无创治疗方法,且在此基础上探讨了癫痫外科治疗未来发展趋势。

康复期脑卒中患者日间过度嗜睡现状及影响因素研究

目的调查康复期脑卒中患者日间过度嗜睡行为现状及影响因素。方法便利选取189例康复期脑卒中患者作为调查对象,使用一般资料调查表、Epworth嗜睡量表、匹兹堡睡眠指数量表、美国国立卫生研究院卒中量表、汉密顿抑郁量表及中风后身体活动障碍量表进行调查。结果康复期脑卒中患者Epworth嗜睡量表得分为10.00(6.00,14.00)分,日间过度嗜睡发生率为57.67%。多元线性回归分析结果显示,年龄、合并症数量、睡眠质量、神经功能以及抑郁程度是康复期脑卒中患者日间过度嗜睡的主要影响因素(均P<0.05),可解释日间过度嗜睡总变异的31.30%。结论康复期脑卒中患者日间过度嗜睡水平较高,医护人员可结合相应影响因素制定针对性干预措施,以减少患者日间过度嗜睡行为发生。

银杏叶提取物注射液联合双联抗血小板治疗急性脑梗死恢复期患者的效果

目的:银杏叶提取物注射液联合双联抗血小板治疗急性脑梗死(ACI)恢复期患者的效果。方法:回顾性分析2021年2月至2023年2月该院收治的94例ACI恢复期患者的临床资料,依据治疗方法不同将其分为对照组和观察组各47例。两组均给予降脂、抗感染、营养神经等常规治疗,在此基础上,对照组采用双联抗血小板治疗,观察组在对照组基础上联合银杏叶提取物注射液治疗。比较两组临床疗效,治疗前后美国国立卫生研究院卒中量表(NIHSS)评分、血清炎性因子[白细胞介素-6(IL-6)、纤维蛋白原(FIB)]水平、凝血功能指标[凝血酶时间(TT)、凝血酶原时间(PT)、活化部分凝血活酶时间(APTT)、纤维蛋白原(FIB)]水平,以及不良反应发生率。结果:观察组治疗总有效率为93.62%(44/47),对照组治疗总有效率为82.98%(39/47),差异无统计学意义(P>0.05);观察组基本痊愈率为29.79%(14/47),高于对照组的12.77%(6/47),差异有统计学意义(P<0.05)。治疗后,观察组血清FIB、hs-CRP、IL-6水平均低于对照组,TT、PT、APTT值均高于对照组,差异有统计学意义(P<0.05)。两组不良反应发生率比较,差异无统计学意义(P>0.05)。结论:银杏叶提取物注射液联合双联抗血小板治疗ACI恢复期患者可提高临床疗效,减轻神经功能损伤,降低炎性因子水平,改善凝血功能,效果优于单纯双联抗血小板治疗。

浅谈RKEF工艺回转窑内衬施工工艺及使用效果

镍具有很好的可塑性、耐腐蚀性和磁性等性能,主要被用于钢铁、镍基合金、电镀及电池等领域。目前冶炼镍主要以红土镍矿为原料,以RKEF工艺为主。红土镍矿在回转窑进一步升温脱去自由水和结晶水且部分发生预还原反应。回转窑作为RKEF冶炼工艺的关键设备,其使用的稳定性及使用寿命直接影响到生产的稳定及产量。作为回转窑不可缺少的内衬耐火材料是制约其使用稳定性及使用寿命的关键因素。以印尼某公司年产30万tRKEF镍铁项目回转窑耐火材料的施工工艺展开,简要阐述了回转窑内衬耐火材料的结构和施工工艺。经过多年应用实践,对回转窑内衬浇注料结构进行了改良并对施工工艺进行了优化,回转窑内衬使用寿命由最初的15个月左右,现在使用寿命已经提升到了超过30个月,并且回转窑使用的稳定性也得到了很大的提高。

牵正散合活血通络汤治疗脑梗死恢复期风痰瘀阻证患者疗效及神经功能缺损的影响

目的:探讨牵正散合活血通络汤对治疗脑梗死恢复期风痰瘀阻证患者疗效及神经功能缺损的影响。方法:选取2022年5月~2023年4月在我院就诊的脑梗死恢复期的患者106例,采用随机数字表法将患者分成对照组和观察组,各53例。对照组给予常规西药治疗,观察组在对照组的基础上采用牵正散合活血通络汤治疗,两组均持续治疗12周。比较两组中医症候积分、临床疗效、神经功能缺损情况和日常生活能力[美国国立卫生院卒中量表(NIHSS)和改良Barthel指数(MBI)量表]、血液流变学参数及安全性。结果:治疗后,2组主症、次症及总分较治疗前降低,观察组更低(P<0.05)。观察组临床总有效率高于对照组(88.68%vs.71.70%,P<0.05)。治疗后,两组NIHSS评分降低,MBI评分升高(P<0.05),与对照组相比,观察组NIHSS评分更低,MBI评分则更高(P<0.05)。与治疗前相比,治疗后2组低切全血黏度、红细胞比容及纤维蛋白原水平均下降(P<0.05),观察组上述血液流变学参数较对照组均下降(P<0.05)。两组不良反应总发生率比较(对照组7.55%vs.观察组1.89%),差异无统计学意义(P>0.05)。结论:脑梗死恢复期风痰瘀阻证患者运用牵正散合活血通络汤治疗可缓解临床症状,提高疗效,促进神经功能修复,提升日常生活能力,改善血液流变学,且不增加不良反应。

认知与行为护理联合精准动态延伸护理在神经内科难治性癫痫患者中的应用研究

目的:探讨认知与行为护理联合精准动态延伸护理在神经内科难治性癫痫患者中的应用研究。方法:选取2021年1月—2022年1月南阳市中心医院收治的102例神经内科难治性癫痫患者作为研究对象,将其随机分为实验组(51例)与常规组(51例)。常规组实施精准动态延伸护理,实验组在常规组的基础上进行认知与行为护理,护理时间均为3个月。对比两组患者护理期间自我效能评价量表(GSES)、癫痫发作次数和护理前后生活质量。结果:护理后,实验组患者GSES评分均高于常规组,差异有统计学意义(t=10.152,P<0.05);实验组患者护理期间癫痫发作次数少于常规组,差异有统计学意义(t=28.346,P<0.001);护理后,实验组患者生活质量评分均高于常规组,差异有统计学意义(t=6.744,P<0.05)。结论:认知与行为护理联合精准动态延伸护理能够改善神经内科难治性癫痫患者自我效能、降低癫痫发作次数,还可提高患者的生活质量。

集束化护理在脑卒中患者康复期的应用及对不良事件的影响

目的探讨集束化护理在脑卒中康复期患者中的应用效果。方法78例脑卒中康复期患者随机分为两组,对照组实施常规护理,观察组在对照组基础上实施集束化护理,比较两组的神经功能、生活质量、肌力和不良事件。结果护理4周后,观察组的NIHSS评分低于对照组,SS-QOL评分高于对照组,肌力分级优于对照组(P<0.05)。观察组的不良事件总发生率低于对照组(P<0.05)。结论集束化护理有助于促进脑卒中康复期患者的神经功能恢复,改善其肌力和生活质量,降低不良事件发生风险。

耳穴贴压联合血栓通注射液对缺血性脑卒中恢复期吞咽障碍及神经功能的影响

目的:观察耳穴贴压联合血栓通注射液对缺血性脑卒中恢复期吞咽障碍及神经功能的影响。方法:选取82例气虚血瘀证缺血性脑卒中恢复期患者,按随机数字表法分为对照组及治疗组各41例。对照组予以常规治疗,治疗组在对照组基础上予以耳穴贴压联合血栓通注射液治疗。2组均治疗4周。比较2组临床疗效,比较2组治疗前后吞咽功能[吞咽功能量表(SSA)、洼田饮水试验、Metrohealth评分]、神经功能[神经功能缺损评分(NIHSS)、加拿大神经病学量表(CNS)、神经恢复功能量表(MRS)]、血液流变学指标值、血清指标值[C-反应蛋白(CRP)、白细胞介素-6(IL-6)]的变化。结果:治疗4周后,治疗组临床疗效总有效率为95.12%,对照组为78.05%,2组比较,差异有统计学意义(P<0.05)。治疗后,2组SSA评分、洼田饮水试验评分、Metrohealth评分均较治疗前下降(P<0.05),治疗组上述3项评分均低于对照组(P<0.05)。治疗后,2组NIHSS评分、MRS评分均较治疗前下降(P<0.05),CNS评分均较治疗前升高(P<0.05);治疗组NIHSS评分、MRS评分均低于对照组(P<0.05),CNS评分高于对照组(P<0.05)。治疗2周、4周后,2组全血高切黏度、血小板聚集率均较治疗前下降(P<0.05),治疗组全血高切黏度、血小板聚集率均低于同一时间段对照组(P<0.05)。治疗2周、4周后,2组血清CRP、IL-6水平均较治疗前下降(P<0.05),治疗组血清CRP、IL-6指标值均低于同一时间段对照组(P<0.05)。结论:耳穴贴压联合血栓通注射液能有效改善缺血性脑卒中恢复期患者的吞咽功能、神经功能,改善血液高凝状态,减少炎症反应,提高临床疗效。

奥拉西坦联合高频重复经颅磁刺激对脑梗死恢复期康复情况的影响研究

目的观察奥拉西坦联合高频重复经颅磁刺激(rTMS)对脑梗死恢复期康复情况的影响。方法选择商丘市中医院2021年10月至2023年4月收治的110例脑梗死患者为研究对象开展前瞻性研究,以计算机随机分组法将其列为联合组(55例)和对照组(55例),对照组实施常规治疗联合rTMS治疗,联合组在对照组的基础上采用奥拉西坦辅助治疗,开展为期6个月随访,比较两组患者的治疗效果及预后情况。结果不同方案治疗后,联合组的核因子E2相关因子2(Nrf2)、血红素氧合酶1(HO-1)、醌氧化还原酶1(NQO-1)蛋白表达水平均高于对照组(P<0.05);联合组的超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)均高于对照组,丙二醛(MDA)低于对照组(P<0.05);联合组的脉搏波波速(WV)、脑血管动态阻力(DR)、血管阻力指数(RI)均低于对照组(P<0.05);联合组治疗7 d、14 d后的神经功能缺损量表(NIHSS)评分及改良Rakin量表(mRs)评分均低于对照组;随访期间,联合组的不良事件发生率7.27%(4/55)低于对照组21.82%(12/55),差异具有统计学意义(P<0.05)。结论奥拉西坦联合rTMS能有效改善脑梗死恢复期患者的抗氧化力,并减轻应激损伤,对促进患者脑血流动力学、神经功能康复并改善预后均有积极意义。