皮质酮混合异丙酚对大鼠海马脑片CA1区长时程增强的影响

异丙酚是目前临床常用的静脉全麻药物,但是一些应用 异丙酚的患者在术后表现出遗忘等记忆功能障碍,这可能 与异丙酚影响突触的可塑性有关。皮质酮是啮齿类动物 重要的糖皮质激素,应激反应可以使动物体内皮质酮水平增 高,可抑制大鼠海马脑片长时程增强(LTP)的形成。长时 程抑制(LTD)和LTP是突触可塑性的重要形式,单独应用皮     

长时程增强及长时程抑制与全麻药关系的研究进展

长时程增强(long-term potentation,LTP)和长时程抑制(long-term depression,LTD)作为突触可塑性的两种不同表达方式,是学习记忆活动的细胞水平的生物学基础,与记忆的形成和维持有关.近年来许多研究表明,全身麻醉药的遗忘、镇静催眠及镇痛等效应与影响神经系统的突触可塑性即LTP和LTD有密切的关系.现就近年来LTP及LTD与全身麻醉药之间的最新进展作一综述.     

钙黏蛋白在突触发育和突触可塑性调节中的作用

背景 钙黏蛋白（cadherin）是一类存在于细胞表面的跨膜糖蛋白,最初被认为是一种钙离子依赖性的细胞黏附分子,主要参与调节细胞黏附、促进细胞增殖、维持细胞极性等过程.近几年对cadherin调节突触发育和突触可塑性的研究取得了较大进展. 目的 围绕cadherin在突触发育和突触可塑性过程中的作用及其相关分子机制简要作一综述,旨在为神经系统疾病的治疗提供理论依据. 内容 Cadherin的概述,cadherin在突触发育和突触可塑性调节中的作用以及相关分子机制,cadherin与神经疾病. 趋向 随着cadherin在调节突触发育和突触可塑性过程中的研究不断深入,cadherin将成为治疗神经疾病的一个新型的靶点.     

蛋白激酶Mζ维持长时记忆机制的研究进展

背景突触的长时程增强（long-term potentiation,LTP）作为神经系统可塑性与学习记忆机制的经典电生理模型已得到广泛研究,LTP诱导阶段的分子机制已明确,但在记忆存储阶段维持信息的分子机制目前仍不清楚。蛋白激酶Mζ（protein kinaseMζ,PKMζ）是一种具有持续活性的蛋白激酶C的亚型,是维持LTP及长时记忆的必要分子。目的现就当前PKM‘维持长时记忆机制的研究及其进展作一综述。内容分别描述了PKMζ的概述、记忆存储的分子机制、记忆擦除和相关疾病4个方面的内容。趋势人们将对PKMζ在保存信息、维持长时记忆中的作用及其可能机制进行更深入的研究。     

异丙酚对新生大鼠海马CA1区兴奋性突触反应的影响

目的：研究异丙酚对新生大鼠海马CAI区兴奋性突触反应的影响。方法：取1周龄Wistar大鼠,快速断头取脑,用振动切片机切取400μm厚的海马脑片,电刺激靠近海马CA1区的Schaffer纤维,用全细胞膜片钳技术记录CA1区锥体细胞的兴奋性突触后电流（excitatory post—synaptic current,EPSC）。循环液中加入不同浓度的异丙酚,观察其对EPSC的影响。然后给与低频刺激（900pulse,3Hz）诱导长时程抑制（10ng—term depression,LTD）,并观察异丙酚对LTD诱导的影响。结果：异丙酚呈剂量依赖性地抑制EPSC,其怍用可被印防己毒素（picrotoxin,pic）阻断;异丙酚可易化由N-甲基-D-门冬氨酸（N—methvl—D—aspartate,NMDA）受体介导的LTD的诱导。结论：异丙酚可影响新生大鼠海马CA1区的兴奋性突触传递和突触可塑性,从而对大鼠的学习和记忆产生影响。     

神经病理性痛大鼠海马突触长时程增强的变化

目的 探讨神经病理性痛大鼠海马突触长时程增强(LTP)的变化.方法 成年雄性Wistar大鼠18只,体重190～240 g,随机分为3组(n=6):对照组(C组)、假手术组(S组)和神经病理性痛组(NP组).采用结扎左侧L4,5脊神经的方法 制备大鼠神经病理性痛模型.对照组不制备模型;假手术组仅暴露左侧L4,5脊神经.于模型制备后7、14和21 d时观察大鼠痛行为学及足部形态;于模型制备前(基础状态)、制备后7、14和21 d时测定痛阈;于最后一次痛阈测定结束后3 d时记录海马CA1区兴奋性突触后电位(EPSP),以高频刺激(HFS)诱发LTP,LTP为HFS后EPSP峰值较基础值增大10%以上且维持时间≥60 min,行LTP分级,以评价其程度.结果 NP组模型制备后痛阈低于基础值及C组和S组,LTP程度高于C组和S组(P<0.05).结论 神经损伤可易化大鼠海马CA1区突触LTP,提示神经病理性痛可能与海马突触LTP的易化有关.     

孕期吸入异氟醚对子代大鼠海马神经元突触可塑性的影响

目的 探讨孕期吸入异氟醚对子代大鼠海马神经元突触可塑性的影响.方法 孕14 d的SD大鼠10只,体重220～250 g,采用随机数字表法,将孕鼠随机分为对照组和异氟醚组,每组5只.对照组大鼠每天单纯机械通气2 h,异氟醚组大鼠每天吸入1.3%异氟醚2 h,至大鼠分娩.子代大鼠出生后4周,采用Morris水迷宫实验测定认知功能,测定结束后处死子代大鼠取脑,分离海马,采用透射电镜观察海马CA1区神经元突触的超微结构,计数海马神经元突触数量,测定突触后致密物质厚度.结果 与对照组相比,异氟醚组子代大鼠逃避潜伏期延长,穿越平台次数减少,海马神经元突触数量减少,突触后致密物质厚度降低(P<0.05).结论 孕期吸入异氟醚可通过抑制子代大鼠海马神经元突触的可塑性而降低其认知功能.     

孕期吸入异氟醚对子代大鼠海马神经元突触可塑性的影响

目的 探讨孕期吸入异氟醚对子代大鼠海马神经元突触可塑性的影响.方法 孕14 d的SD大鼠10只,体重220～250 g,采用随机数字表法,将孕鼠随机分为对照组和异氟醚组,每组5只.对照组大鼠每天单纯机械通气2 h,异氟醚组大鼠每天吸入1.3%异氟醚2 h,至大鼠分娩.子代大鼠出生后4周,采用Morris水迷宫实验测定认知功能,测定结束后处死子代大鼠取脑,分离海马,采用透射电镜观察海马CA1区神经元突触的超微结构,计数海马神经元突触数量,测定突触后致密物质厚度.结果 与对照组相比,异氟醚组子代大鼠逃避潜伏期延长,穿越平台次数减少,海马神经元突触数量减少,突触后致密物质厚度降低(P<0.05).结论 孕期吸入异氟醚可通过抑制子代大鼠海马神经元突触的可塑性而降低其认知功能.     

七氟醚抑制突触后胆碱能突触传递而不影响短时程增强

背景：目前人们已了解全身麻醉对兴奋性和抑制性突触的作用。但全身麻醉影响突触可塑性，从而影响学习和记忆的机制在细胞水平上尚不清晰。本研究选取体细胞一体细胞之间一致的突触后神经元，验证临床浓度的七氟醚是否影响胆碱能突触传递的短时程增强。     

慢性脑低灌注大鼠认知功能和突触可塑性变化

目的建立一种与脑动静脉畸形有关的慢性脑低灌注动物模型,研究慢性脑低灌注对大鼠认知功能和突触可塑性变化的影响。方法建立慢性脑低灌注动物模型并设立鼠龄相匹配的对照组,术后3个月,采用水迷宫实验评价各组动物认知功能,神经可塑性采用免疫组化和蛋白印迹方法检测各组动物海马区组织中MAP-2,GAP-43和突触素表达。结果水迷宫实验检测发现模型组动物寻找平台的潜伏期较对照组明显延长,模型组动物在平台象限停留时间和跨越平台象限次数较对照组明显减少。模型组动物海马组织中MAP-2和突触素的表达较对照组明显降低,而两组动物之间GAP-43的表达水平未见明显差异。结论慢性脑低灌注可诱导大鼠认知功能障碍,可能与动物海马组织中MAP-2和突触素表达减少有关。     

Reduction of Plasma Fibrinogen, Immunoglobulin G, and Immunoglobulin M Concentrations by Immunoadsorption Therapy with Tryptophan and Phenylalanine Adsorbents

Abstract Immunoadsorption (1A) therapy with tryptophan (TR-350) or phenylalanine (PH-350) adsorbents has been used to reduce the concentration of serum antibodies in human lymphocyte antigen (HLA)-immunized patients. Other forms of plasma purification have been reported to reduce the level of fibrinogen, which affects the blood properties. In this study we investigated the effects of IA therapy using both adsorbents on plasma fibrinogen and immunoglobulins G and M in 13 patients (8 patients were treated with TR-350, and 5 patients were treated with PH-350). During each session 1 plasma volume (2.8 ± 0.4 L of plasma) was processed through the immunocolumn and then returned to the patient together with the blood cells. Compared with the pretreatment values, the plasma fibrinogen, IgG, and IgM concentrations were significantly reduced after IA therapy (p < 0.01 for TR-350; p < 0.04 for PH-350). There was a positive correlation between the degree of reduction of plasma proteins and the number of IA treatments given. A nonpara-metric test (Wilcoxon's signed-rank test or the Mann-Whitney test) was used for statistical analysis. We conclude from our study that IA therapy effectively lowers the plasma levels of fibrinogen, IgG, and IgM and thus can be considered a valuable alternative to other blood purification methods.     

Is the recovery profile of mivacurium independent of the rate of decay of its plasma concentration in patients with normal plasma cholinesterase activity?

Background: The duration of action of muscle relaxants is poorly correlated to the rate of decay of their plasma concentration. The plasma concentration of mivacurium may rapidly decrease below its active concentration because of the extensive hydrolysis of mivacurium. By inflating a tourniquet on one upper limb for 3 min after the administration of atracurium, mivacurium or vecuronium, we studied the influence of the initial decline of their plasma concentration on their effect. Methods: In 50 patients anaesthetised with thiopental, isoflurane and fentanyl, the effect of bolus doses of 0.15 or 0.25 mg . kg^?1 mivacurium (MIV 15, MIV 25), 0.3 or 0.5 mg . kg^?1 atracurium (ATR 30, ATR 50) and 0.06 or 0.1 mg . kg^?1 vecuronium (VEC 06, VEC 10) were measured on both arms (evoked response of the adductor pollicis to train-of-four stimulation every 12 s), a tourniquet being applied on one arm just before and during 3 min after the muscle relaxant bolus. Results: Tourniquet inflation of 3 min almost abolished the neuromuscular effect of mivacurium. In the vecuronium groups and in the ATR 50 group, tourniquet inflation did not modify the maximum degree of depression of the twitch response. Also, the duration of action of vecuronium was unaffected by the tourniquet. In the ATR 30 group, times to return of the twitch response to 25% (duration 25%) and 75% (duration 75%) of control response were significantly shorter in the cuffed arm, 23 min vs 27 min, and 41 min vs 45 min, respectively. In the ATR 50 group, only duration 25% was significantly shorter in the cuffed arm (41 min vs 45 min). Conclusion: The results suggest that the rate of decline of the plasma concentration of mivacurium is so rapid, that a very low and almost clinically ineffective concentration is present as soon as 3 min after its administration. The results also indicate that the recovery from a mivacurium-induced neuromuscular blockade is not influenced by the rate of decay of its plasma concentration in patients with genotypically normal plasma cholinesterase.     

Membranes in Artificial Organs

Abstract: Membrane processes play a pivotal and enabling role in modern replacement therapy for acute and chronic organ failure and in the management of immunologic diseases. In fact, virtually all contemporary extracorporeal blood purification methods employ membrane devices, and the next generation of artificial organs and tissue engineering therapies are almost certain to be similarly grounded in membrane technology. In this short essay, we comment on the similarities and differences among synthetic membranes and their natural counterparts and also provide a critical overview of the demographics and technology of hemodialysis, hemofiltration, apheresis, oxygenation, and emerging membrane technologies and applications.     

The multiply injured child

Blunt trauma is the principal cause of childhood death in many developed countries. This review outlines the differences between adults and children with respect to resuscitation and treatment of orthopaedic injuries in a child with polytrauma. Recent advances in techniques of fracture stabilization are reported.     

Dilemma of Membrane Biocompatibility and Reuse

Abstract: Numerous articles have been published on the multiple use of dialyzers and on the effect of different reprocessing chemicals and techniques on the dialyzer biocompatibility and performance. The results often appear contradictory, especially those comparing standard biocompatibility parameters. Despite this confusion, a discerning review of the published works allows certain limited conclusions to be drawn. Reprocessing of used hemodialyzers changes the biocompatibility profile of a dialyzer as defined by the parameters complement activation. leukopenia, and cytokine release. The effect of reprocessing depends on the chemicals and reprocessing technique applied and also on the type of membrane polymer being subjected to the reprocessing procedure. Reports of pyrogenic reactions indicate that the flux of the membrane also influences how suitable it is for safe reuse. An increased risk of allergic and pyrogenic reactions appears to be associated with dialyzer reuse. Furthermore, there has been a lack of investigations into the immunologic effect of the layer of adsorbed and chemically altered proteins that remains on the inner surface of reprocessed dialyzers. We conclude that the clinical benefit of dialyzer reuse cannot be generally accepted from a biocompatibility point of view.     

The analgesic effect of racemic ketamine in patients with chronic ischemic pain due to lower extremity arteriosclerosis obliterans

Background : Ketamine in sub-dissociative doses has been shown to have analgesic and phantom-Limb pain, where conventional treatment has often failed. Chronic ischemic pain due to lower extremity arteriosclerosis obliterans often responds poorly to analgesics, and the pain-generating mechanisms are not well understood.
Methods : Eight patients with rest pain in the lower extremity due to arteriosclerosis obliterans were given sub-dissociative doses of 0.15, 0.30, or 0.45 mg/kg racemic ketamine and morphine 10 mg as a 5-min infusion on four separate days in a cross-over, double-blind, randomised protocol. Plasma levels of (S)- and (R)-ketamine and their nor-metabolites were analysed with an enantioselective high-performance liquid chromatography (HPLC) method. Pain levels were evaluated with a visual analogue scale (VAS).
Results : Individual pain levels were highly variable during and after all the infusions but the pooled pain levels showed a dose-dependent analgesic effect of ketamine with a transient but complete pain relief in all patients at the highest dose (0.45 mg/ kg). Side-effects, mainly disturbed cognition and perception, were pronounced and dose-dependent. Morphine 10 mg had an analgesic peak at 20 min and 5/8 patients had complete pain relief. The remaining 3 patients also had high baseline pain scores, indicating a higher analgesic potency for the 0.30 and 0.45 mg/ kg ketamine doses than for morphine 10 mg.
Conclusion : We have demonstrated a potent dose-dependent analgesic effect of racemic ketamine in clinical ischemic pain. Due to a narrow therapeutic window, this analgesic effect is probably best utilised in combination with other analgesics.     

Intravenous endotoxin does not increase tissue extravasation of albumin in rats

Background : It is unclear whether activation of the inducible nitric oxide synthase (iNOS) increases or decreases the extravasation of plasma.
Methods : Chloralose anaesthetised male Wistar rats received E. coli lipopolysacharide (LPS), 3 mg kg^-1 i.v., or the corresponding volume of saline, 3 or 5 h before the end of the experiment. Mean arterial pressure (MAP) and heart rate (HR) were recorded. Tissue clearance of radio-labelled albumin, during the last 2 h of each experiment, was determined by a double-isotope method. In separate animals, the serum concentration of nitrite and nitrate was determined, 5 h after LPS or the solvent.
Main Results : LPS initially decreased MAP and lastingly increased HR. In the 3-h LPS animals (n=8), tissue plasma clearance was lower in the heart and calf muscle and increased only in diaphragm, compared to corresponding control animals (n=8). In the 5-h LPS rats, clearance was lowered (n=8) in the entire gastrointestinal tract and in testes, compared to controls (n=8). The serum nitrite/nitrate concentration was higher in animals given LPS (n=6) than in controls (n=6).
Conclusion : After LPS, tissue clearance of albumin was not increased in any major tissue, in spite of increased serum levels of NO end products. Apparently, after activation of iNOS, the augmented release of NO is not necessarily associated with increased albumin extravasation.     

Adrenaline markedly improves thoracic epidural analgesia produced by a low-dose infusion of bupivacaine, fentanyl and adrenaline after major surgery: A randomised, double-blind, cross-over study with and without adrenaline

Background: Basic pharmacological research indicates that there are synergistic antinociceptive effects at the spinal cord level between adrenaline, fentanyl and bupivacaine. Our clinical experience with such a mixture in a thoracic epidural infusion after major surgery confirms this. The objectives of the present study were to evaluate the effects on postoperative pain intensity, pain relief and side effects when removing adrenaline from this triple epidural mixture. Methods: A prospective, randomised, double-blind, cross-over study was carried out in 24 patients after major thoracic or abdominal surgery. Patients with only mild pain when coughing during a titrated thoracic epidural infusion of about 10 ml · h^?1 of bupivacaine 1 mg · ml^?1, fentanyl 2 μg · ml^?1, and adrenaline 2 μg · ml^?1 were included. On the 1^st and 2^nd postoperative days each patient was given a double-blind epidural infusion, at the same rate, with or without adrenaline. The effect was observed for 4 h or until pain when coughing became unacceptable in spite of a rescue analgesic procedure. Rescue analgesia consisted of up to two epidural bolus injections per hour and i.v. morphine if necessary. All patients received rectal paracetamol 1 g, every 8 h. Fentanyl serum concentrations were measured with a radioimmunoassay technique at the start and end of each study period. Main outcome measures were extent of sensory blockade and pain intensity at rest and when coughing, evaluated by a visual analogue scale, a verbal categorical rating scale, the Prince Henry Hospital pain score, and an overall quality of pain relief score. Results: The number of hypaesthetic dermatomal segments decreased (P <0.001) and pain intensity at rest and when coughing increased (P <0.001) when adrenaline was omitted from the triple epidural mixture. This change started within the first hour after removing adrenaline. After 3 h pain intensity when coughing had increased to unacceptable levels in spite of rescue analgesia (epidural bolus injections and i.v. morphine). Within 15–20 min after restarting the triple epidural mixture with adrenaline, pain intensity was again reduced to mild pain when coughing. Serum concentration of fentanyl doubled from 0.22 to 0.45 ng · ml^?1 (P <0.01), and there was more sedation during the period without adrenaline. Conclusions: Adrenaline increases sensory block and improves the pain-relieving effect of a mixture of bupivacaine and fentanyl infused epidurally at a thoracic level after major thoracic or abdominal surgery. Serum fentanyl concentrations doubled and sedation increased when adrenaline was removed from the epidural infusion, indicating more rapid vascular absorption and systemic effects of fentanyl.