P-糖蛋白对卡马西平和苯妥英钠通过大鼠血脑屏障影响的研究

目的观察P糖蛋白(Pglycoprotein,PGP)拮抗剂维拉帕米对卡马西平和苯妥英钠通过大鼠血脑屏障的影响,探讨PGP在难治性癫癎多药耐药机制中的作用。方法在健康大鼠大脑皮质内安置微透析探针,腹腔注射卡马西平(20mg/kg)和苯妥英钠(50mg/kg),在给药后不同时间点收集透析液,并用高效液相技术检测其中的药物浓度,通过微透析探针局部给予维拉帕米,观察后者能否提高大鼠皮质脑细胞外液中抗癫药物的浓度。结果维拉帕米升高了脑细胞外液中卡马西平[60min:(1.74±0.28)μg/ml,90min:(1.87±0.31)μg/ml]和苯妥英钠[30min:(1.08±0.30)μg/ml;60min:(1.54±0.22)μg/ml;150min:(0.91±0.19)μg/ml]的药物浓度,前者在给药后60～90min显著增高(P<0.05),后者在给药后30～150min显著增高(P<0.05)。结论PGP限制卡马西平和苯妥英钠顺利通过血脑屏障,降低脑皮质细胞外液抗癫癎药物浓度,难治性癫时PGP表达增加可能是引起患者对抗癫癎药物产生多药耐药的原因。     

多药转运蛋白对癫痫大鼠脑内奥卡西平浓度的影响

目的 观察多药转运蛋白家族的成员P-糖蛋白(P-glycoprotein,PGP)和多药耐药蛋白(multi-drug re-sistance associated protein,MRP)对匹罗卡品慢性癫痫大鼠模型海马内神经元细胞外液中奥卡西平浓度的影响,证明奥卡西平是否为PGP和MRP的底物,探讨PGP和MRP参与难治疗性癫痫耐药的机制.方法 建立匹罗卡品慢性癫痫动物模型,将32只大鼠分为对照组、模型组、维拉帕米干预组、丙磺舒干预组(每组8只),于腹腔注射奥卡西平(80 mg/kg)后30、60、90、120、150 min,通过微透析及高效液相色谱技术,检测大鼠海马神经元细胞外液中的药物浓度.结果 维拉帕米干预后,癫痫大鼠海马细胞外液中奥卡丙平的浓度于给药后90～120 min(1.26±0.09、0.93±0.10)明显高于模型组(0.87±0.06、0.66 4±0.04),两组比较有统计学差异(P<0.05);丙磺舒干预后60～150 min,大鼠海马内细胞外液中奥卡两平的浓度(1.07±0.11、1.32±0.13、1.02±0.10、0.87±0.08)显著高于模型组(0.81±0.08、0.87±0.06、0.66±0.04、0.58±0.06)(P<0.05).结论 奥卡西平是PGP和MRP的底物,PGP和MRP能够选择性的将奥卡西平泵出血脑屏障外,降低癫痫病灶内的药物浓度,上述机制可能参与了难治性癫痫患者对奥卡西平产生耐药.     

多药转运蛋白对匹罗卡品癫(癎)大鼠模型脑内拉莫三嗪浓度的影响

目的 观察多药转运蛋白[P-糖蛋白(P-glycoprotein,PGP)和多药耐药相关蛋白(multi-drug resistance associated protein,MRP)]对匹罗卡品慢性癫(癎)大鼠模型海马内拉莫三嗪浓度的影响,探讨PGP和MRP在难治性癫(癎)多药耐药机制中的作用.方法 建立匹罗卡品慢性癫(癎)动物模型,在模型大鼠海马内安置微透析探针,腹腔注射拉莫三嗪(10mg/kg)后于不同时间点收集透析液,并用高效液相色谱检测其中的药物浓度.通过微透析探针局部分别给予PGP拮抗剂维拉帕米和MRP拮抗剂丙磺舒,观察维拉帕米和丙磺舒对模型鼠海马内神经元细胞外液拉莫三嗪浓度的影响.结果 维拉帕米明显升高了癫(癎)大鼠海马细胞外液拉莫三嗪的药物浓度,在给药后60、90、120、150 min(0.65±0.11、0.84±0.09、0.70±0.09和0.58±0.08)与模型组(0.41±0.10、0.50±0.04、0.39±0.09和0.30±0.06)比较差异有统计学意义(F=5.01、8.61、10.23、7.89,P<0.05),丙磺舒也提高了海马内拉莫三嗪的浓度,给药后90、120、150 min(0.75±0.09、0.58±0.10和0.49±0.07)与模型组比较差异有统计学意义(F=6.58、4.56、4.75,P<0.05).结论 PGP和MRP均能够限制拉莫三嗪通过癫(癎)大鼠血脑屏障,从而降低了海马内拉莫三嗪的药物浓度,上述机制可能参与了难治性癫(癎)耐药的发生.     

多药耐药相关蛋白与难治性癫痫

难治性癫痫的发病机制尚不完全清楚,近年来发现在难治性癫痫患者病灶脑组织可检测出多药耐药相关蛋白(MRP)的过度表达,表明MRP与难治性癫痫耐药关系密切。MRP的过度表达受多种因素影响,其可能通过降低抗癫痫药物在血脑屏障的通透性,减少药物的有效浓度,从而引起抗癫痫药物耐药发生。鉴于MRP在难治性癫痫多药耐药中可能的重要作用,筛选非MRP底物的抗癫痫药物和选用适合长期服用的特异性强﹑安全性高﹑毒副作用性小的MRP抑制剂,可能会为今后临床治疗难治性癫痫翻开新的一页。     

多药耐药相关蛋白-1在难治性颞叶癫痫患者脑组织中的表达及丙磺舒的干预作用

目的 观察难治性颞叶癫痫患者脑组织中多药耐药相关蛋白1( MRPl)及应用MRP1拮抗剂丙磺舒干预后的表达,探讨MRP1与难治性颞叶癫痫多药耐药的关系.方法 应用免疫组化检测难治性颞叶癫痫患者脑组织实验组和对照组MRP1的表达情况,同时应用免疫蛋白印记(Western blot)方法检测实验组、丙磺舒干预组和对照组MRP1的表达.结果 免疫组化结果显示MRP1在难治性颞叶癫痫患者脑组织中表达增强,与对照组比较差异有显著性(P＜0.05).Western blot结果显示丙磺舒干预组MRP1蛋白水平较实验组明显较少,差异有显著性(P＜0.05).结论 脑内高表达的MRP1参与难治性颞叶癫痫的耐药机制,丙磺舒可以降低脑组织内MRP1的表达.     

难治性癫痫大鼠脑内多药耐药相关蛋白1表达的研究

目的 研究杏仁核电刺激点燃的难治性癫痫大鼠脑内多药耐药相关蛋白1（multidrug resistant-associated protein 1 MRP1）表达的情况.方法 建立杏仁核电刺激点燃的难治性癫痫大鼠模型,用免疫组织化学及免疫蛋白印记（western blot）的方法,分析比较MRP1蛋白在癫痫模型组与正常对照组的表达.结果 药物难治性癫痫大鼠组脑内多药耐药相关蛋白的表达显著高于正常对照组（P〈0.01）.在癫痫大鼠脑内广泛分布的MRP1免疫阳性细胞主要为毛细血管内皮细胞和星形胶质细胞.结论 癫痫大鼠脑内高表达的MRP1参与了难治性癫痫的耐药机制.     

海人酸致难治性癫痫大鼠脑组织及外周血P糖蛋白表达趋势相关性研究

目的 研究难治性癫痫大鼠脑组织及外周血中P糖蛋白表达的相关性,探讨难治性癫痫可能的耐药机制,并比较海人酸在不同核团致痫后P糖蛋白表达的差异.方法 用海人酸分别于大鼠杏仁核及海马进行化学点燃,制作难治性癫痫模型.采用免疫组化方法,分析比较难治性癫痫大鼠脑组织及外周血中P糖蛋白的表达.结果 杏仁核点燃组与海马点燃组大鼠脑组织及外周血P糖蛋白表达高于与其相对应的生理盐水卡马西平组及生理盐水对照组,有统计学意义(P＜0.05);杏仁核生理盐水卡马两平组及海马生理盐水卡马西平组大鼠脑组织及外周血P糖蛋白的表达高于杏仁核生理盐水对照组及海马生理盐水对照组,有统计学意义(P＜0.05);杏仁核点燃组和海马点燃组大鼠脑组织及外周血P糖蛋白的表达相近,无统计学意义(P＞0.05).结论 难治性癫痫大鼠外周血及脑组织中P糖蛋白的表达具有一定的相关性,难治性癫痫的耐药机制可能是癫痫本身、服用抗癫痫药物等多因素作用的结果.杏仁核点燃模型及海马点燃模型均可诱导相近似的P糖蛋白的表达.     

抗癫痫药物对人癫痫病灶脑片癫痫样电活动的抑制作用

目的：探讨用手术切除的癫痫病灶进行抗癫痫药物研究的可行性。方法：将手术中切除大脑皮层病灶切成脑薄片，通过脑标本的降温通氧保存脑片活力，用低Ｍｇ＾２＋和４－氨基吡啶（４－ＡＰ）灌流诱导脑片自发性癫痫样放电，用自行研制的多孔溶槽实现对同一脑标本行４种药物实验，观察在抗癫痫药前后自发放电波幅度变化。结果：４例癫痫病灶及２例非癫痫脑组织（对照组）实施了药物敏感实验，常用的４种药物实验，观察在抗癫痫药前后自发放电波幅变化。结果：４例癫痫病灶及２例非癫痫组织（对照组）实验了药物敏感实验，常用的４种抗癫痫药在低浓度时（μｍｏｌ／Ｌ：苯妥英钠１００，苯巴比妥１０００，安定３０，卡马西平１００）对癫痫脑片自发放电的抑制作用较对非癫痫脑片的作用弱。药物浓度增大３倍后，对两组脑片均产生明显抑制作用。结论：癫痫病灶皮层脑片在体外可以用     

顽固性癫痫病人脑部多药耐受基因的表达

癫痫病人中有10％～20％尽管血药浓度正常但仍不能用药物控制发作,耐药机理可能与脑实质内药物浓度不当有关。许多抗痫药,如苯妥英钠、苯巴比妥、卡马西平的化学结构与由多药耐受基因     

53种抗癫癎中成药的成分分析

目的：检测部分抗癫痫中成药中是否含有西药抗癫痫药物的成分。方法：用高效液相色谱法测定53种抗癫痫中成药中是否含有苯巴比妥、苯妥英钠、卡马西平和丙戊酸钠。结果：83.01%中成药中测出含有苯巴比妥、苯妥英钠、卡马西平和丙戊酸。结论：市场上大量未标明含有抗癫痫西药成分的中成药,严重影响癫痫用药安全。     

Early stages in the formation of the cerebellum in the frog

The formation of the cerebellum was studied during the first 6 months of the tadpole stage of the bullfrog by using standard histological methods and reconstructions from serial horizontal sections. Three major developmental phases were noted in the formation of the cerebellum. (1) During the first 5 weeks of development, the neuroepithelium proliferated and the dorsal mesencephalic plates increased in size. (2) Starting in the sixth week, a patch of neuroepithelium began to differentiate and gave rise to a small population of Purkinje cells. In subsequent weeks, the area of differentiation continued to spread and a Purkinje cell layer became established along the dorsal margin of the cerebellar plate. (3) In the 12th week, the ventrolateral part of the cerebellar plate began to increase in size and generate two populations of small cells. The lateralmost part of the neuroepithelium in this area generated a group of cells that formed an external granular layer that was one cell deep. Cells of this external granular layer migrated inward into the primitive molecular layer, and by the 26th week only a remnant of an external granular layer remained in the cerebellum. The more medially situated part of the neuroepithelium gave rise to another population of small cells that formed a column, which appeared to be continuous with the Purkinje cells, but differed from them in size. It should be noted that full maturation of the cerebellum occurs during metamorphosis, which in this species remains some 2 years away.     

Inhomogeneities in the propagation of the slow wave in the stomach

The propagation of the slow wave in the stomach and its role in inducing sweeping peristaltic contractions toward the pylorus, essential for a proper digestion and emptying, have been studied for many years. Irregularities in the timing or in the pattern of propagation of the slow wave have been known to induce various gastric malfunctions and, recently, several types of gastric dysrhythmias have been described which could lead to gastric contraction abnormalities. In this study, Du et al. have analyzed the disturbances caused by a simple transmural incision in a human stomach, performed to obtain a biopsy of the muscle, on the propagation pattern of the slow wave. In addition, they show that such an incision may by itself also induce new types of gastric dysrhythmias. These results are important in demonstrating that the function of the stomach can easily be disturbed by such procedures. This mini‐review describes several ways in which inhomogeneities in propagation may affect the conduction pattern of the slow wave, including the genesis of several dysrhythmias, and what is currently known about their impact on gastric contraction and digestion.     

Local nonuniformities in the syncytium of the horizontal cells of the retina in the turtle

Electrical coupling between horizontal cells of the turtle retina was investigated by means of two microelectrodes (current and recording ones) penetrating neighbouring cells at a fixed distance from each other. The morphological coupling was revealed by means of fluorescent dye Lucifer Yellow. The electrical coupling was confirmed between elements of similar type (L1--axonal terminals, or L2--cell bodies, or R/G type cells) and no coupling was found between elements of different types, though L1 and L2 are directly connected through thin axons. In the L1 syncytium the electrical coupling at small (less than or equal to 50 microns) but fixed distances between microelectrodes could differ several times depending on the minimal displacement of microelectrodes. This local nonuniformity of coupling can be explained on the basis of structural nonuniformities in the L1 (axon terminal) network. It is unlikely however that the structural nonuniformities can influence the functional properties of horizontal cell network when the retina is stimulated adequately (by light).     

Asymmetry in the structural organization of the ganglion layer of the retina in the frog

Silver-impregnated retinal preparations were used to study the distribution density and topographic features of small and large ganglionic cells (GC) of Rana ridibunda and Rana temporaria. For both species the increased density of GC (a streak) stretched higher than the naso-temporal axis passing through the optic disk. Beyond the streak the density of small GC was maximal in the central zone of the retina and decreased towards its periphery. For the upper quadrants of the retina the density of small GC was higher than that for the lower ones by 26% on the average. On the contrary, the density of large GC was higher in the lower part of the retina as compared to the upper one, the difference being more pronounced for R. temporaria. The density of large GC was also asymmetric with respect to the dorso-ventral axis being higher in nasal quadrants than in temporal ones by 40-55%. The highest density of large GC was found in the middle zone of the retina. The found structural asymmetry in the retinal output raster may bear an adaptively ecological meaning and may condition the particularities of the formation of the visually guided prey-catching and avoidance reactions.     

Challenges in the Management of the HIV Patient in the Third Decade of AIDS

The epidemic of AIDS has been increasingly recognized as a major health and socioeconomic problem, not only in the United States or Africa, but also the rest of the world. The face of the epidemic has changed. The role that mental health providers play has also significantly grown as the epidemic continues on. Prior to the introduction of Highly Active Anti-Retroviral Therapy (HAART) and other advances in HIV care, the patients faced issues that related to death and dying. These advances brought with them renewed hope and resurrected lives. The patients fought with issues related to living new lives with HIV no longer an imminent death threat. In the third decade of AIDS, the struggles of the post-HAART era continue but bring with it more challenges. Mental health providers need to familiarize themselves with these issues so that they can better help HIV patients cope with this devastating disease.     

Role of the subthalamo-nigral input in the control of amygdala-kindled seizures in the rat

The substantia nigra pars reticulata (SNpr) is a critical site for the control of epileptic seizures. Potentiation of the inhibitory GABAergic input from the striatum to the SNpr suppresses primary or secondary generalized seizures in the rat. The purpose of this study was to examine the possible involvement of the excitatory glutamatergic input from the subthalamic nucleus to the SNpr in the control of both the electroencephalographic and the motor components of amygdala-kindled seizures in the rat. Microinjections of either an N-methyl- -aspartate (NMDA) antagonist in the substantia nigra or a GABA_A agonist in the subthalamic nucleus, significantly reduced motor seizures but did not modified the afterdischarges. These results provide evidence for the involvement of the subthalamo-nigral projection in the modulation and the propagation of the motor components of amygdala-kindled seizures.     

Patterning in the regeneration of electroreceptors in the fin of Kryptopterus

The influence of the target tissue on afferent nerve regeneration was studied in the adult glass catfish, Kryptopterus. In this fish, electroreceptors in the anal fin are distributed in a characteristic pattern in the proximal part of the fin and are absent in the distal portion of the fin. We tested whether axons were more likely to induce electroreceptors in certain regions of fin epidermis than in others. We rotated fin transplants so that the location of the degenerating electroreceptors was altered with respect to the regenerating axons in the host tissue dorsal to the fin. The effects of these rotations were observed in the living animal with differential interference contrast optics over a period of 10 weeks. When transplants were reversed rostrocaudally, new electroreceptors formed in the caudal half of the interradial zone, where degenerating electroreceptors were at the time of transplantation. When transplants were rotated so that the dorsoventral and rostrocaudal axes were reversed, some new receptors formed in the old target site regions that were located in the caudal interradial zones (in the distal half of the graft with respect to the host). Regenerating axons reached these regions of the transplant by taking unusual routes around the electroreceptor-free regions of fin. Very few electroreceptors formed in the distal/caudal or proximal/caudal interradial quadrants of grafts where the original orientation of the tissue was maintained. We suggest that old target sites have a neurotropic influence on the regenerating afferent axons and discuss the possibility that the distal fin epidermis is not as permissive to electroreceptor formation as proximal fin epidermis.     

Pursuit of the origin of the large myelinated fibers of the anterolateral funiculus in the spinal cord in humans in relation to the pathomechanism in amyotrophic lateral sclerosis

To determine the origin of the large myelinated fibers in the anterolateral funiculus (ALF) in the spinal cord of humans, myelinated fibers in the ALF of the mid-cervical spinal cord were examined quantitatively. Five groups of subjects were examined, consisting of control subjects, patients with cerebral lesions and showing complete degeneration of the unilateral/bilateral pyramis of the medulla oblongata, those with lesions of the pontine tegmentum, those with lesions of the lower cervical spinal cord, and those with thoracic/lumbar lesions. The results indicate that the large myelinated fibers in the ALF of the mid-cervical spinal cord of humans originate from the tegmentum of the brain stem and the lower cervical spinal cord, and not from the cerebrum, or the thoracic or lumbar spinal cord. Thus, they are descending fibers from the brain stem tegmentum and ascending fibers from the lower cervical cord, and not corticospinal tracts or long-ascending fibers from the thoracic or lumbar spinal cord. The origin of the large myelinated fibers in the ALF of the spinal cord in humans, the number of which was severely decreased in patients with amyotrophic lateral sclerosis, is considered to be the long-descending neurons in the brain stem tegmentum and the propriospinal neurons in the spinal cord. Received: 23 December 1998 / Revised, accepted: 29 March 1999     

Organization in the descending tracts of the dorsolateral funiculus in the cat

Organization of the fibers in the descending tracts of the dorsolateral funiculus of the cervical spinal cord was investigated in cats. The spinal cord was penetrated with microelectrodes at 400 mum intervals in the medio-lateral direction at the c5/c6 and c6/c7 segmental borders. Silicon substrate microelectrodes with a linear arrangement of activated iridium contacts were used. The stimulus consisted of a 20 ms train of charge balanced biphasic current pulses at 330 Hz. The evoked activities from selected forelimb muscles were acquired into computer. Only the data points with an activation threshold of less than 35 muA were considered in the analysis. Muscle contractions were mostly in the form of short twitches. In both spinal segments, an area of high threshold was found in the middle of the dorsolateral funiculus. Majority of the muscles studied had a dorsal or ventral concentration of activation points. The distal muscles were mostly activated in the ventro-lateral aspect of the funiculus, while the elbow muscle maps spread to both dorsal and ventral sides. These results show a functional organization in both cervical segments studied, with overlapping regions between the areas dedicated for each forelimb muscle.     

Selectivity between faces in the responses of a population of neurons in the cortex in the superior temporal sulcus of the monkey

There is a population of neurons in the cortex in the middle and anterior part of the superior temporal sulcus (STS) of the monkey with responses which are selective for faces. If, consistent with the effects of damage to the temporal lobe, these neurons are involved in face recognition or in making appropriate social responses to different individuals, then it might be expected that at least some of these neurons might respond differently to different faces. To investigate whether at least some of these neurons do respond differently to different faces, their responses were measured to a standard set of faces, presented in random sequence using a video framestore. It was found that a considerable proportion of the neurons with face selective responses tested (34/44 or 77%) responded differently to different faces, as shown by analyses of variance. An index of the discriminability of the most and least effective face stimulus (d') ranged between 0.2 and 5.0 for the different neurons. Although these neurons often responded differently to different faces, they did not usually respond to only one of the faces in the set, so that information that a particular face had been shown was present across an ensemble of neurons, rather than in the responses of an individual neuron. These findings indicate that the responses of these neurons would be useful in providing information on which different behavioral responses made to different faces could be based. These neurons could thus be filters, the output of which could be used for recognition of different individuals and in emotional responses made to different individuals.