电穿孔过程中细胞膜电导率变化条件下的跨膜电压研究

基于经典球形单细胞五层介电模型,并考虑电穿孔过程中细胞膜电导率的变化,对微秒脉冲电场作用下的细胞内外膜跨膜电压进行了仿真分析,以及脉冲电场诱导人宫颈癌细胞系Hela凋亡的实验研究。仿真分析发现,随着细胞穿孔程度的加剧,细胞膜电导率增加,内、外膜跨膜电压的比值不断增加,表明外加脉冲电场对内膜的影响不断增强,其作用靶点逐渐透过细胞膜进入胞内细胞器。同时,实验结果也表明随着脉冲电场场强不断增加,微秒脉冲电场所诱导的Hela细胞的凋亡率随之增加,从而间接证实了仿真分析的结果。现有研究普遍认为微秒脉冲电场的作用靶点为细胞外膜,本研究关于微秒脉冲电场对细胞内膜作用的研究结果是对已有研究的重要补充和发展。     

脉冲电磁场对细胞模型特异性作用机理研究

采用简化的细胞电学模型分析脉冲电磁场对细胞膜跨膜电位的影响，证明在低强度电磁脉冲对细胞的作用，跨膜电位的直接影响不是主要的，而细胞膜上的“微孔”，在电磁脉冲的刺激下逐步扩大，形成让离子通过的穿膜通道才是主要的作用过程，并应用电穿孔效应解释瞬态电磁脉冲对细胞的作用。     

不同中心频率下双极电脉冲的生物医学效应分析

采用多层球对称细胞模型,针对恶性Tonsillar B细胞和Jurkat T淋巴细胞,利用电路分析方法,计算了不同中心频率的一阶高斯脉冲在细胞各部分的电压分布;给出了中心频率与细胞膜跨膜电压间的定量关系和细胞核膜电穿孔的最佳频率;研究了细胞膜电穿孔和纳秒脉冲致DNA降解的原因。本文工作为双极瞬态脉冲应用于恶性肿瘤治疗提供了参考。     

背根神经节电穿孔转染神经元技术的改进

文题释义：背根神经节：具有一组不同的感觉神经元，向大脑传递不同的感觉刺激，如疼痛、温度、触摸和身体姿势。背根神经节电穿孔是基因转染中通过非病毒的方式以物理方法转染神经元的技术。 周围神经损伤：各种原因导致周围神经支配区域的感觉、运动及营养障碍。文献报道周围神经损伤常伴随损伤近端的神经元胞体的肿胀、尼氏体消失、细胞核偏移；损伤远端轴突发生华勒氏变性、许旺细胞增殖等现象。 背景：背根神经节电穿孔技术是一种研究神经再生的高效基因转染方法，以往背根神经节电穿孔的电压条件使得标记的神经元及轴突数目较少，统计误差较高。 目的：提高神经元及其轴突的标记率，为周围神经再生的研究提供理论依据。 方法：以增强型绿色荧光蛋白为观察指标优化背根神经节电穿孔技术在神经元轴突再生方面的应用。将ICR小鼠随机分为2组，分别行背根神经节电穿孔手术，检测在35 V和60 V电压干预下神经元及其轴突的标记率。 结果与结论：①35 V和60 V电压未造成神经元明显死亡；②与35 V电压相比，60 V电压条件下标记的神经元及其轴突数量显著增加，且通过损伤部位的轴突数量明显增多(P < 0.05)；③60 V电压对实验动物未造成行为功能损害；④结果表明，60 V电压能够使神经元及其轴突的标记率增高，其结果能够为周围神经元轴突再生研究提供依据。 ORCID: 0000-0001-8681-1346(齐士斌) 中国组织工程研究杂志出版内容重点：干细胞；骨髓干细胞；造血干细胞；脂肪干细胞；肿瘤干细胞；胚胎干细胞；脐带脐血干细胞；干细胞诱导；干细胞分化；组织工程     

电穿孔技术的研究及应用进展

脉冲电场的电穿孔效应在医学上的应用是一门多学科的生物医学工程学技术,已证实其主要的生物学效应是使靶细胞膜发生可逆及不可逆性电击穿。近年电穿孔效应所介导的电化学治疗应用广泛。对电脉冲的量—效关系、电场分布、膜穿标记物及生物电阻成像等基础研究及临床应用中的进展及尚存问题作一综述。     

子宫内电穿孔转染胎鼠脑室管膜下区神经干细胞的条件优化

背景:神经干细胞是一群可以自我增殖并具有多向分化潜能的细胞.子宫内电穿孔转染可将RNA或质粒瞬时转入活体小鼠神经干细胞内对目的基因进行干扰或过表达,是目前活体研究大脑皮质发育的最直接可靠的研究方法.目的:以胚胎小鼠脑室管膜下区的神经干细胞为目标,以增强型绿色荧光蛋白作为报告基因,优化子宫内电穿孔转染的条件,为研究大脑皮...     

基于不可逆电穿孔胰腺肿瘤消融的最优空间覆盖模型

目的 在传统的消融手术中,医生通过观察患者的二维影像对肿瘤大小、位置、形态进行粗略估算从而进行手术方案规划。这种方式严重依赖医生的主观经验和专业技能,极易造成消融范围过大或不彻底,增加了术后并发症的风险。因此,科学的术前规划和精准的消融电极及电场作用区域定位具有非常重要的意义。本文提出一种胰腺肿瘤最优空间覆盖模型算法,以为胰腺肿瘤不可逆电穿孔消融提供最佳电场作用区域。方法 基于单根双极高压脉冲电极产生的电场消融区域为椭球体,在椭球长轴方向与电极导入路径即胰管方向相同、球心在胰管上及长短轴轴长满足一定比例关系的约束条件下,首先利用积极集算法求解球心,再借助Rodrigues旋转求解正定矩阵,得到的椭球即为电场作用区域,然后对长短轴轴长比值进行迭代寻优,最后将肿瘤在椭球中的占比作为评价指标以寻找最小消融椭球即最优电场作用区域。本文在公开数据集MSD上进行广泛实验寻找每个病例肿瘤的最小消融椭球及其占比。结果 最小消融椭球与肿瘤的几何形状及其距胰管的位置密切相关,对于大多数病例,肿瘤在最小消融椭球中的占比在20%～50%之间,最高能达到59.5%。结论 本文提出的算法可为胰腺肿瘤不可逆电穿孔消...     

直流脉冲场作用下穿孔悬液细胞跨膜电压计算模型

细胞膜穿孔期间,膜电导率大幅度提高,正常生理条件下的悬液细胞跨膜电压(Transmembranevoltage,TMV)计算模型不再适用。我们建立了高强度直流脉冲电场作用下,均匀悬液中穿孔细胞跨膜电压的计算模型。首先将膜电导率不均匀分布的穿孔悬液细胞等效为一小球,然后根据有效介质理论求出细胞悬液的平均场,用其代替难于精确求解的实际场,最后利用穿孔单细胞膜电压计算公式,建立悬液中穿孔细胞膜电压的计算模型。模型表明在穿孔期间,细胞膜跨膜电压和外加电场大小,细胞膜穿孔临界角,细胞半径,细胞质、细胞膜和膜外溶液的电导率、细胞排列以及细胞浓度等参量有关。     

电脉冲致离体S-180细胞电穿孔的观察与研究

扫描电镜下我们观察到了一定强度电脉冲致 S- 180细胞电穿孔的现象。同时分别改变电压、电容、脉冲个数 ,对 S- 180离体细胞进行电脉冲作用 ,通过苔盼蓝追踪 ,发现在一定的条件下 ,随着对 S- 180离体细胞电穿孔的电压越大、电容越小、脉冲个数越多 ,其穿孔百分率越大。     

高功率脉冲微波和电磁脉冲辐照对心肌细胞膜电穿孔效应及机理的研究

电磁辐射可造成人体多器官系统的损伤。对其损伤的病理机制至今尚未完全阐明。心脏是电磁辐射损伤的敏感器官之一。本实验拟通过研究HPPM和EMP对心肌细胞的影响,探讨电磁辐射致伤的关键机制,解释脉冲电磁场致心肌细胞损伤的发展规律。本实验采用HPPM和EMP辐照原代培养心肌细胞的方法,用原子力显微镜、激光扫描共聚焦显微镜、流式细胞仪和全自动生化检测仪等多种实验手段,检测辐照对细胞膜形态、结构和功能的影响。结果发现HPPM和EMP辐照后,心肌细胞搏动减慢,形态异常,活力下降,凋亡和坏死率明显增加。细胞膜出现数量不等、大小不一的电穿孔,细胞膜通透性丧失,结构破坏,细胞培养液中Na 、K 、Ca2 、Cl-、Mg2 、Ca2 和无机磷离子浓度显著升高(P<0.01),细胞内Ca2 浓度显著降低(P<0.01)。结果提示心肌细胞是电磁辐射损伤的敏感细胞,脉冲电磁场可致心肌细胞膜电穿孔,细胞形态、结构和功能均受到严重损伤。电穿孔效应是解释电磁辐射非热效应的关键机制之一。电穿孔导致的细胞膜通透性和膜结构改变存在一定发展规律。     

Dual-frequency method for synchronous measurement of cell capacitance,membrane conductance and access resistance on single cells

A dual-frequency method was developed to monitor changes of membrane capacitance, membrane conductance and serial resistance between patch pipette and cytoplasm of the cell in the whole-cell configuration. Measurement of real and imaginary components of cell admittance during excitation with two superimposed sinusoidal voltages of different frequencies provides mathematical solutions for all three variables. The validity of the method was verified with experiments on mast cells and exocrine pancreatic acinar cells. During degranulation of mast cells, induced by GTPS in the pipette solution, a stepwise increase in membrane capacitance could be observed, indicating that the resolution of the method is below 10 fF. Precalibration of the setup allows all calculated data to be expressed as absolute values. The capacitance measurement proved to be rather independent of changes in the access resistance and in the cell membrane resistance over a wide range. The huge changes in membrane conductance of mouse pancreatic acinar cells during hormonal stimulation with acetylcholine produced a relative error of less than 0.3% in the capacitance trace. This allows a clear distinction between changes of membrane conductance and cell capacitance. The method therefore offers great advantages in the study of exocytosis as well as endocytosis in cell types, such as exocrine gland cells, with major changes in membrane conductance during hormonal stimulation.     

电磁波作用下人体的电场应力计算

本文从电场应力的角度研究稳态平面波和脉冲波对人体作用的计算,主要讨论了振幅为100、随正弦规律变化的稳态平面波以及核爆炸脉冲波作用下人体内电场应力的分布,并给出了部分计算结果.     

家兔红细胞阻抗谱的实验和等效电路拟合研究

目的：研究家兔红细胞阻抗谱并建立RC等效电路模型参数。方法：在0．01MHz-100MHz频率范围，使用Agilent 4294A阻抗分析仪测量了家兔红细胞交流阻抗，通过Bode图、Nyquist图、Nicols图、Randles图的曲线拟合分析，比较三个RC等效电路模型的拟合残差。结果：（1）家兔红细胞阻抗谱的第一特征频率fc1=2．5MHz，第二特征频率fc2=5．25MHz；（2）等效电路模型，模型3的拟合误差小于模型1和模型2；（3）等效的单个红细胞膜电容约为0．458／μF／cm^2。结论：家兔红细胞阻抗谱表现出两个特征频率，其等效电路模型以模型3形式更为合理。     

高压纳秒脉冲电场杀伤化疗抗性肿瘤细胞的实验机理研究

肿瘤严重危害人类生命和健康,化疗抵抗是当前临床肿瘤治疗所面临的主要屏障之一。为探究高压纳秒脉冲电场是否能够对化疗抵抗的肿瘤细胞具有同等敏感性,以肺癌细胞系A549及顺铂化疗抵抗的A549/R为研究对象,用80个脉冲宽度为200 ns,场强为5~15 kV/cm的纳秒脉冲作用后分析对比其活性情况、致死效应及消融阈值差异。结果表明:当场强为8、10、15 kV/cm纳秒脉冲电场作用下A549/R细胞的存活率分别为5.65%、7.78%、2.80%,显著低于A549(分别为48.31%、26.8%、5.96%);诱导的凋亡和坏死率也显著高于A549(P<0.05);在80个宽度为200 ns,场强为15 kV/cm的脉冲作用下,A549/R单层细胞消融面积是A549的1.59倍;A549/R的消融阈值为～8 kV/cm,显著低于A549(～13 kV/cm)。因此,纳秒脉冲电场为可优先选择杀伤化疗抵抗的A549/R细胞,诱导更高的凋亡率、消融面积,并且有更低的消融阈值。高压纳秒脉冲对化疗抵抗的肿瘤细胞的选择性作用,可望作为一种新型的物理选择方式联合其他肿瘤治疗方法,克服肿瘤治疗临床难点,为化疗抵抗或高恶性度的肿瘤消融提供新策略。     

Influence of barium on the effects of phenylalanine in proximal tubules

The present study was designed to further test for the role of peritubular potassium conductance in the repolarization of peritubular cell membrane during sustained stimulation of sodium coupled transport by phenylalanine. To this end the potential difference across the peritubular cell membrane (PDpt) has been recorded continuously, while 10 mmol/l phenylalanine (Phe) were added to the luminal perfusate, both in the presence or absence of peritubular or luminal barium (1 mmol/l). In the absence of phenylalanine and barium, PDpt amounts to –65.5±2.2 mV. Phe leads to a rapid depolarization of the peritubular cell membrane by +36.2±2.2 mV within 30 s, followed by an almost complete repolarization by –28.9±2.6 mV within 7 min. In the presence of barium in peritubular perfusate, the depolarization following Phe is +24.3±2.6 mV and the repolarization almost abolished (–4.3±0.9 mV). In the presence of barium in luminal perfusate, Phe leads to a depolarization by +35.7±2.4 mV followed by a repolarization of –17.0±3.2 mV within 7 min. It is concluded that the repolarization during sustained stimulation of sodium coupled transport is in large part due to alterations of peritubular potassium conductance.     

Early effects of aldosterone on the basolateral potassium conductance of A6 cells

Summary Aldosterone increases the basolateral conductance in target epithelia. The basolateral membrane of tight epithelia contains two different types of K⁺ conductances (G_K), a resting and a volume-activated G_K. We have studied the early effects (at 4 hours) of 500 nmol/l aldosterone on the basolateral membrane G_k of A6 cells (a Xenopus laevis kidney cell line), after the permeabilization of the apical membrane with amphotericin B. In the presence of a 97 to 3 mmol/l apical to basolateral K⁺ gradient, the resting, inward rectifying G_K was similar in control and aldosterone treated cells. In contrast, aldosterone induced a 2-fold increase of the volume-activated quinidine sensitive G_K.     

基于Hammerstein模型的腕关节功能电刺激控制技术研究

非线性系统的控制通常比较复杂,基于模型辨识的自适应控制方法可以有效地提高控制精度和稳定性。本文根据功能电刺激(FES)下腕关节运动的非线性和时变性特点,利用Hammerstein模型,实现了腕关节运动的FES建模及辨识。通过M序列和逆M序列激励信号,将FES腕关节运动模型分为线性时变和静态非线性两部分。考虑到静态非线性部分的特点,在运动控制过程中只需要根据线性时变特点确定相应的自适应调节策略,将一个复杂非线性问题简化为线性控制问题。对腕关节运动的FES仿真实验也验证了方法的有效性。     

The effect of phenylalanine on the electrical properties of proximal tubule cells in the frog kidney

The present study was designed to elucidate the effects of sodium-coupled transport on the electrical properties of proximal tubule cells in the isolated perfused frog kidney. Cable analysis techniques have been employed to determine the resistance of the luminal and peritubular cell membranes in parallel (R _m) and the apparent ratio of the luminal over the peritubular cell membrane resistance (VDR). Furthermore, the sensitivity of the potential difference across the peritubular cell membrane (PD_pt) to 6-fold increases of peritubular potassium concentration (PD_k) was taken as a measure of the relative potassium conductance of this membrane. In the absence of luminal phenylalanine, PD_pt amounts to –60±1 mV (n=90),R _m to 36±3 k cm (n=22), VDR to 1.81±0.14 (n=20), and PD_k to 15.0±0.9 mV (n=25). The application of 10 mmol/l phenylalanine replacing 10 mmol/l raffinose leads to a rapid (within 30 s) depolarisation of PD_pt to 50±5% of its control value and to a delayed (within 12 min) recovery to 95±5% of control. The rapid depolarisation is associated with a decline ofR _m and VDR, indicating a decrease mainly of the luminal cell membrane resistance. During recovery of PD_pt there is a parallel increase of VDR and a further decline ofR _m pointing to a decline of the basolateral cell membrane resistance. PD_k is decreased during rapid depolarisation but increases again during the recovery phase. Thus, phenylalanine initially decreases but then increases above control the apparent potassium conductance. Removal of phenylalanine leads to a transient hyperpolarisation and increased apparent potassium conductance. If a cell is depolarised by current injection into a neighbouring cell, a similar decrease of PD_k is observed which shows also a similar recovery (partial repolarisation) despite continued injection of constant current. The data point to a potential-dependent peritubular K⁺-conductance (of the inwardly rectifying type) and to a regulatory increase within some ten minutes, when the cell is depolarised either by sodium entry across the luminal cell membrane or by current injection into a neighbouring cell.