A new method for spatially selective,non-invasive activation of neurons: concept and computer simulation

Currently available non-invasive neurostimulation devices, using skin electrodes or externally applied magnetic coils, are not capable of producing a local stimulation maximum deep inside a homogeneous conductor, because of a fundamental limitation inherent to the Laplace equation. In this paper, a new neurostimulation method (the DeepFocus method) is presented, which avoids this limitation by using an indirect method of producing electric currents inside tissues: First, cylinder-shaped ferromagnetic rotating disks of non-permanent magnetic material are placed near the skin and magnetized by a non-rotating magnetic coil. Each of the disks rotates at high speed around its own axis of symmetry, thus producing a purely electric Lorentz force field having a non-zero divergence outside the disk, and therefore giving rise to charge accumulations inside the tissues. Subsequently, the magnetic field is switched off suddenly, causing a re-distribution of charge, and hence short-lived electrical currents, which can be used to activate neurons. Two magnet configurations are presented in this paper, and analyzed by computer simulation, showing that the DeepFocus method produces a maximum current density (the ‘focus’) deep inside the conducting body. The field strength thus created in the focus (7.9 V/m) is strong enough to activate thick myelinated fibers, but can be kept below the threshold for C-fibers, which makes the new method a possible tool for pain mitigation by targeted neurostimulation.     

胎儿胸腺发育中DNES细胞的表达及其生物学意义

目的:检测胎儿胸腺中弥散神经内分泌系统(diffuseneuroendocrinesystem,DNES)细胞的表达,初步探讨胎儿胸腺发育中DNES细胞的表达及其生物学意义。方法:18～40周胎儿胸腺组织,共15例,采用免疫组织化学SP法,检测嗜铬素A(chromograninA,CgA)和神经元特异性烯醇化酶(neuronspecificenolase,NSE)在胸腺组织中的表达。结果:CgA和NSE在18～38周胸腺中均表达,27～28周前随胎龄增加表达渐增多,之后则渐减少,39周及40周未见表达。CgA和NSE阳性细胞主要分布于胸腺髓质:髓质胸腺细胞之间的阳性细胞呈圆形或椭圆形;胸腺小体周边的阳性细胞呈圆、椭圆或梭形。NSE阳性神经纤维在髓质形成纤维网,部分绕血管走行,形成血管周围丛。结论:胎儿胸腺中存在DNES细胞,它们可能对胎儿期胸腺细胞的发育、分化及成熟起到一定的调控作用。     

高压氧对大鼠脑缺血后NOS阳性神经元的影响

目的　探讨一氧化氮合酶 (NOS)阳性细胞在大鼠急性局灶性脑缺血 /再灌注损伤和高压氧 (HBO)治疗后表达的变化。方法　应用血管内细丝栓堵大脑中动脉 (MCA)的局灶性脑缺血大鼠模型 ,利用黄递酶 -NADPH组织化学方法 ,观察MCA缺血 1h ,再灌注 4、11、2 3、71hNOS阳性细胞在视交叉平面梗死区皮层、视前区、纹状体外侧区和纹状体内侧区域分布的变化 ,在以上期间应用 0 2 5MPaHBO于开始缺血后 2、9、2 1、4 5和 6 9h分别治疗 1次 (1h)。结果　脑缺血后 ,在上述区域形态改变的NOS阳性细胞数随着再灌注时间的延长逐渐增多。HBO治疗后 ,各时间点在皮层、视前区和纹状体内侧区 ,形态改变的NOS阳性细胞数明显减少 (P <0 0 5 ) ,而纹状体外侧区无明显变化 (P >0 0 5 )。结论　HBO可明显抑制大鼠急性局灶性脑缺血 /再灌注损伤区NOS阳性细胞的变性     

微小RNA-21对脊髓缺血再灌注损伤后神经元细胞凋亡的影响

目的 :探讨微小RNA-21(miR-21)能否抑制FASL的表达进而减少脊髓缺血再灌注损伤后神经元细胞的凋亡。方法:通过慢病毒载体转染PC-12细胞,测定最佳的感染复数(MOI)。分别转染不同的慢病毒载体建立并验证上调miR-21、下调miR-21和对照的PC-12细胞体系,经过氧糖剥夺以及复糖复氧处理模拟脊髓损伤后缺血再灌注损伤过程。利用Hoechst/PI染色技术检测上调以及下调miR-21对PC-12细胞凋亡情况的影响;利用q RT-PCR技术以及Western blot技术检测上调以及下调miR-21表达对PC-12细胞中FASL表达水平的影响。在293T细胞中,通过质粒转染技术分别建立miR-21/miR-21阴性对照和FASL野生型/FASL突变型/FASL阴性对照的共转染体系,利用双荧光素酶实验验证miR-21和FASL的靶向关系。结果:MOI=20为最佳的感染复数。在该条件下进行慢病毒转染72h后,荧光显微镜下可观测到绝大多数PC-12细胞中有明显的绿色荧光,通过q RT-PCR技术检测miR-21的水平发现:上调组的miR-21水平较对照组明显提高(P0.05);但是下调组miR-21水平和对照组相比却没有明显变化(P0.05)。转染三种不同慢病毒的PC-12细胞经过氧糖剥夺及复氧处理后,Hoechst/PI双染法检测结果证实上调组细胞凋亡较对照组明显减少(P0.05),而下调组的细胞凋亡比例较对照增高(P0.05)。另外,氧糖剥夺及复氧处理后,三组PC-12细胞中FASL表达水平均较处理前增高,而上调组的FASL水平较对照组均下降(P0.05),下调组的FASL水平较对照组有所升高(P0.05)。双荧光素酶实验结果发现miR-21在FASL野生型(3′UTR-WT)组间有显著差异(P0.05),而miR-21在FASL对照组以及FASL突变型组间无显著差异(P0.05)。结论 :miR-21能够通过靶向抑制FASL表达,减少脊髓缺血再灌注损伤后神经元的凋亡。     

西比灵治疗脑出血继发脑水肿及ET-1、NSE的测定

目的　探讨西比灵治疗脑出血继发脑水肿的疗效及作用机制。方法　 90例脑出血患者随机分为西比灵治疗组 5 0例 ,常规治疗对照组 40例 ,常规治疗组进行常规治疗 ,西比灵治疗组应用常规治疗 +西比灵 5mg ,每晚口服 ,共 2 0天 ,并分别在治疗前、治疗后 3、2 0天进行病情评分及ET 1、NSE测定并与对照组进行疗效对比。结果　 (1)西比灵治疗组的临床疗效优于常规治疗组 (P <0 .0 5 ) ;(2 )西比灵治疗后ET 1、NSE浓度明显低于治疗前 (P <0 .0 1) ,随着病程的延长 ,二者血浆含量有下降趋势 ,与脑水肿密切相关。结论　 (1)西比灵治疗脑出血继发脑水肿具有肯定疗效 ;(2 )ET 1、NSE血浆浓度测定可能成为脑出血继发脑水肿诊断及疗效评估的客观指标。     

华佗再造丸对大鼠局灶性脑缺血损伤的保护作用

目的 探讨华佗再造丸(HTZZ)对大鼠局灶性脑缺血再灌注损伤后缺血半暗带的神经元及胶质细胞的保护作用。方法 采用大鼠局灶性大脑中动脉阻断(MCAO)模型,于缺血再灌注(I/R)后第22、70小时分别进行神经功能评分(NDS);TTC染色测定脑梗死体积;免疫组织化学的方法测定烯醇化酶(NSE)和胶质纤维酸性蛋白(GFAP)的动态变化。结果 HTZZ治疗组与对照组相比,在大鼠I/R后22、70 h NDS均明显增高(P<0.05);脑梗死体积明显缩小(P<0.05);NSE的表达明显增强(P<0.05);GFAP的表达均较对照组明显减少(P<0.05);在I/R后70 h GFAP的表达较22 h时略有增加(P>0.05)。结论 HTZZ对大鼠局灶性脑缺血再灌注损伤后缺血半暗带的神经元及胶质细胞有显著的保护作用,是一种有效的神经保护剂。     

人胚胎大脑海马发育的超微结构研究

本文借助电子显微镜技术对４ 月胎龄组及６ 月胎龄组水囊引产胎儿海马中段部位的神经细胞进行了超微结构观察、拍照,并对照片给予分析、讨论。结果显示：６ 月组部分神经细胞中细胞器较４ 月组发达。该结果可提示人胎儿海马发育中期（４ 月组） 神经细胞功能欠活跃,而到了较晚期（６ 月组） 神经细胞功能增强,细胞器发育较完善,功能活跃。     

Neuroprotective effects of water-soluble Ganoderma lucidum polysaccharides on cerebral ischemic injury in rats

Aim of the study

To investigate the neuroprotective effects of water-soluble Ganoderma lucidum polysaccharides (GLPS) on cerebral ischemic injury in rats, and to explore the involved mechanisms.

Materials and methods

Two models [middle cerebral artery occlusion (MCAO) in Sprague-Dawley (SD) rats and oxygen and glucose deprivation (OGD) in primary cultured rat cortical neurons] were employed to mimic ischemia-reperfusion (I/R) damage, in vivo and in vitro, respectively. Cerebral infarct area was measured by tetrazolium staining, and neurological functional deficits were assessed at 24 h after I/R. Neuronal apoptosis was studied by Nissl staining and DNA fragmentation assay. Neuronal injury was assessed by morphological examination using phase-contrast microscopy and quantified by measuring the amount of lactate dehydrogenase (LDH) leakage, cell viability was measured by sodium 3′-1- (phenylaminocarbonyl)-3, 4-tetrazolium-bis (4-methoxy-6-nitro) benzene sulfonic acid (XTT) reduction. Neuronal apoptosis was determined by flow cytometry, and electron microscopy was used to study morphological changes of neurons. Caspase-3, -8 and -9 activation and Bcl-2, Bax protein expression were determined by western blot analysis.

Results

Oral administration of GLPS (100, 200 and 400 mg/kg) significantly reduced cerebral infarct area, attenuated neurological functional deficits, and reduced neuronal apoptosis in ischemic cortex. In OGD model, GLSP (0.1, 1 and 10 μg/ml) effectively reduced neuronal cell death and relieved cell injury. Moreover, GLPS decreased the percentage of apoptotic neurons, relieved neuronal morphological damage, suppressed overexpression of active caspases-3, -8 and -9 and Bax, and inhibited the reduction of Bcl-2 expression.

Conclusions

Our findings indicate that GLPS protects against cerebral ischemic injury by inhibiting apoptosis by downregulating caspase-3 activation and modulating the Bcl-2/Bax ratio.     

针刺对急性期脑出血大鼠脑组织神经元特异性烯醇化酶表达的影响

目的：观察脑出血大鼠血肿周围脑组织神经元特异性烯醇化酶（neuron specific enolase,NSE）的表达,探讨＂百会＂透＂曲鬓＂头针疗法治疗脑出血的可能作用机制。方法：选取220只健康雄性W istar大鼠,将其中200只大鼠随机分为两组：模型组和针刺组,每组100只,每组再随机分为6h、1d、2d、3d、7d五个亚组,每个亚组20只;而剩余20只作为空白组。采用自体血注入法制备脑出血模型;针刺组针刺病灶侧＂百会＂透＂曲鬓＂穴。应用神经行为学指标观察各组大鼠神经功能缺损程度;在光镜下观察各组大鼠脑组织病理形态学改变;运用免疫组化方法测定不同时间点各组大鼠脑组织中NSE的表达。结果：①空白组的大鼠表现正常;而各造模组大鼠术后均出现不同程度的神经功能缺损,以3d时最为严重。针刺组大鼠神经功能缺损征较模型组有明显恢复,与模型组比较,2d、3d,7d评分,差异统计学意义（P〈0.01）。②光镜下可见模型组血肿周围脑组织坏死、水肿、炎性细胞浸润,神经细胞核固缩、空泡化,毛细血管扩张、充血,3天时最严重。针刺组脑组织逐渐修复,水肿程度较轻,炎性细胞减少。③空白组大鼠脑组织未见NSE阳性细胞表达;而模型组和针刺组大鼠术后均出现不同程度的NSE阳性细胞表达增多现象。模型组大鼠术后6h即出现大量的NSE阳性细胞表达;至3d时达高峰,7d时有所下降。针刺组NSE阳性细胞表达低于模型组,与模型组在相同时间点比较均差异明显（P〈0.01）。结论：①脑出血后大鼠脑组织内NSE表达上调,且其表达水平的变化与脑组织病理形态的改变、神经功能缺损程度相关;②＂百会＂透＂曲鬓＂针刺法可能是通过降低NSE在脑出血大鼠急性期脑组织中的表达、抑制脑水肿的形成,从而保护受损的神经元细胞、促进缺血半暗带的神经元细胞的存活,以达到脑保护的作用。     

神经营养因子4在成年大鼠背根节神经元的分布

目的 探讨神经营养因子4（NT－4）与成年大鼠背根节神经元的关系。方法 本文用特异的NT－4抗血清以免疫组织化学方法观察了NT－4在成年大鼠背根L6节段神经元中的颁由。结果 NT－4的免疫阳性反应物分布背根节的各型神经元,胞浆染色。结论 NT－4可能与成年大鼠背根节神经元的生理功能有关。