Neuroligin1与突触活动的相互作用

背景 Neuroligin1是突触细胞黏附分子(synaptic cell adhesion molecules,SynCAM)的一种,与Neurexin1β及突触后膜致密蛋白95(postsynaptic density protein 95,PSD-95)相结合形成跨突触复合物,这一跨突触信号可以中介使君子酸(a-amino-3-hydroxy-5-methyl4-isoxazole-propionate,AMPA)受体亚基突触靶向和突触前囊泡释放,在学习、记忆和疼痛中均具有重要作用.目的 对Neuroligin1与突触活动的相互作用进行回顾与总结.内容 Neuroligin1可通过调节AMPA受体、N-甲基-D-天冬氨酸(N-methyl-D-aspartic acid,NMDA)受体的突触靶向来参与到突触活动中;相应的,突触活动也能诱导Neuroligin1的裂解和磷酸化,使突触活动趋于平衡.趋向 通过下调Neuroligin1的表达或干扰其与PSD-95蛋白或Neurexin1β的相互作用,可间接抑制AMPA受体的功能,是未来疼痛治疗的研究方向.     

神经突触中枢神经突触膜相关鸟甘酸激酶锚定蛋白参与疼痛调节的研究进展

背景 中枢神经突触膜相关鸟苷酸激酶(membrane-associated guanylate kinase,MAGUK)蛋白家族包含4种突触相关蛋白:PSD-93、PSD-95、SAP-102、SAP-97,它们参与调节谷氨酸突触信号传递,与学习记忆和疼痛等有关. 目的综述神经突触MAGUK锚定蛋白与疼痛相关受体和分子之间的相互作用及其在疼痛信号调节及传递中的作用. 内容 神经突触MAGUK锚定蛋白可通过与N-甲基-D-天冬氨酸(N-methyl-D-aspartate,NMDA)受体、神经元型一氧化氮合酶(neuronal nitric oxide synthase,nNOS)、使君子酸(α-amino-3-hydroxy-5-methy-4-isoxazole propionate,AMPA)受体以及突触细胞黏附分子(synaptic cell-adhesion molecules,Syn CAM)等相互作用参与调节疼痛信号在突触的传递,影响突触传递强度. 趋向 干扰神经突触MAGUK锚定蛋白与疼痛相关受体和重要分子间的相互作用可影响疼痛信号在突触的传递,是疼痛治疗的新靶点.     

切口痛大鼠脊髓背角GluR1-AMPA受体和GluR2-AMPA受体胞浆至胞膜转运的变化

目的 探讨切口痛大鼠脊髓背角含谷氨酸受体1亚基的使君子酸(GluR1-AMPA)受体和含谷氨酸受体2亚基的使君子酸(GluR2-AMPA)受体胞浆至胞膜转运的变化.方法 成年雄性清洁级SD大鼠32只,体重280～ 300 g,6～8周龄,采用随机数表法,将其随机分为2组:正常对照组(C组,n=8)和切口痛组(Ⅰ组,n=24).Ⅰ组大鼠制作右足底切口痛模型.Ⅰ组于术后3h、1d和3d时取8只大鼠,测定累计痛评分(CPS)和机械缩足阈值(PWT).然后处死大鼠,取L3～6节段脊髓背角,采用Western blot法检测胞浆和胞膜GluR1和GluR2亚基的表达,采用免疫共沉淀技术检测脊髓背角Stargazin与GluR1或GluR2亚基的共表达.结果 与C组比较,Ⅰ组CPS评分升高,PWT降低,脊髓背角胞浆GluR1亚基表达下调,脊髓背角胞膜GluR1表达及Stargazin与GluR1共表达上调(P＜0.05或0.01),脊髓背角胞浆和胞膜GluR2及Stargazin与GluR2共表达差异无统计学意义(P＞0.05).结论 切口痛大鼠脊髓背角GluR1-AMPA受体从胞浆转运至胞膜,而GluR2-AMPA受体不发生胞浆至胞膜的转运.     

Stargazin在切口痛大鼠脊髓背角GluR1-AMPA受体胞浆至胞膜转运中的作用

目的 评价Stargazin在切口痛大鼠脊髓背角含谷氨酸受体1亚基的使君子酸(GluR1-AMPA)受体胞浆至胞膜转运中的作用.方法 成年雄性清洁级SD大鼠45只,体重280 ～ 300 g,6～8周龄,采用随机数字表法,将其分为5组:正常对照组(C组)、假手术组(S组)、切口痛+生理盐水组(P组)、切口痛+ Stargazin小干扰RNA(siRNA)组(I组)和切口痛+Stargazin无意义siRNA组(N组).P组、I组和N组分别鞘内注射生理盐水10μl、20 μmol/L siRNA、20μmol/L无意义siRNA 10μl,2次/d,连续3d,4d后制备右足底切口痛模型.切口痛术后3h时测定大鼠累计痛评分(CPS)和机械缩足阈(PWT).然后处死大鼠,取L3-6节段脊髓背角,采用Westem blot法检测胞浆和胞膜GluR1和GluR2亚基表达,采用免疫共沉淀技术检测脊髓背角Stargazin与GluR1或GluR2亚基的共表达.结果 与C组比较,P组和N组CPS评分升高,PWT降低,脊髓背角胞浆GluR1表达下调,脊髓背角胞膜GluR1表达上调,I组CPS评分升高(P＜0.05或0.01);与P组比较,I组CPS评分降低,PWT升高,脊髓背角胞浆GluR1表达上调,脊髓背角胞膜GluR1表达下调,脊髓背角Stargazin和Stargazin与GluR1共表达下调(P＜ 0.05或0.01).结论 Stargazin介导了切口痛大鼠GluR1-AMPA受体从胞浆至胞膜转运.     

突触后密度家族蛋白与疼痛研究进展

PSD是最早在电镜下发现的位于突触后膜的"致密物蛋白质".这种"致密物"是由一系列细胞骨架蛋白结合了多种与突触信号传递相关的分子(包括受体和各种激酶等)构成的特殊结构.其中一些成员,包括NMDA受体、CaMKII、PSD-93及PSD-95,与疼痛的发生、维持及治疗密切相关,并且彼此之间有着"微妙"的相互调节作用.     

海人藻酸受体功能调节机制在脊髓痛觉敏化中的作用

海人藻酸（kainate, KA）受体在中枢神经系统中广泛分布,通过调节外周和中枢感觉神经元之间的兴奋性信号参与疼痛处理。近年研究发现,多个与KA受体功能相关的蛋白在KA受体功能调节机制中发挥重要作用,从而参与伤害性疼痛信号的传递。文章通过综述KA受体特点、KA受体在疼痛通路中的表达与分布以及KA受体功能调节机制,包括...     

NMDA受体与躯体内脏的痛觉调制

NMDA受体是兴奋性氨基酸的特异性受体 ,与神经细胞钙离子内流密切相关 ,参与体内各种信号传递和调节神经元的兴奋性。它由不同的亚基组成 ,这些亚基决定着天然NMDA受体的功能特性 ,其中 ,含NR2B亚基的受体对伤害性感受的传递和调制有重要作用。已有大量研究表明 ,NMDA受体在痛觉中枢敏感化的产生、维持中有重要作用 ;NMDA受体也可能同时介导外周敏感化和内脏痛。     

Homer1蛋白与Ⅰ组代谢型谷氨酸受体在神经病理性疼痛中的作用

神经病理性疼痛(neuropathic pain, NP)的既往研究中关于Homer1蛋白和Ⅰ组代谢型谷氨酸受体(metabotropic glutamate receptor, mGluRs)在疼痛信号转导中的作用相对明确,但它们相互之间的关系并不清楚,在突触后膜中Homer1蛋白和Ⅰ组mGluRs可以相互作用并对疼痛信号转导和疼痛维持有重要影响,Homer1蛋白可能是其中的关键靶点。Homer1b/c作为重要的突触后致密物在突触可塑性调节和突触信号传递中起重要作用。文章综述了Homer1蛋白特殊的果蝇激活蛋白/血管舒张刺激磷酸蛋白同源结构域1(enabled protein of drosophila/vasodilator-stimulated phosphoprotein homology, EVH1)和螺旋卷曲(coiled-coil, C-C)结构在脊髓突触后膜通过与不同突触后蛋白结合产生NP作用,mGluRs在神经损伤模型的潜在作用机制中与上述作用可能存在共同的作用机制。     

AMPA受体介导的突触可塑性与药物依赖

突触可塑性改变是形成药物依赖长期效应的病理基础,兴奋性氨基酸受体在其中起十分重要的作用。近年来的研究表明,多种药物依赖过程与AMPA受体有关。联系药物依赖所致的AMPA受体的变化与神经元的可塑性改变,探讨AMPA受体介导药物依赖的形成机制,可为进一步理解AMPA受体在药物依赖中的作用提供帮助。     

NMDA受体与躯体内脏的痛觉调制

NMDA受体是兴奋性氨基酸的特异性受体，与神经细胞钙离子内流密切相关，参与体内各种信号传递和调节神经元的兴奋性。它由不同的亚基组成，这些亚基决定着天然NMDA受体的功能特性，其中，含NR2B亚基的受体对伤害性感受的传递和调制有重要作用。已有大量研究表明，NMDA受体在痛觉中枢敏感化的产生、维持中有重要作用；NMDA受体也可能同时介导外周敏感化和内脏痛。     

Vasopressor hormone response following mesenteric traction during major abdominal surgery

Background : We investigated the vasopressor hormone response following mesenteric traction (MT) with hypotension due to prostacyclin (PGI₂) release in patients undergoing abdominal surgery with a combined general and epidural anesthesia. Methods : In a prospective, randomized, placebo-controlled study we administered 400 mg ibuprofen (i.v.) in 42 patients scheduled for abdominal surgery. General anesthesia was combined with epidural anesthesia (T4-L1). Before as well as 5, 15, 30, 45, and 90 min after MT we recorded plasma osmolality, hemodynamics and measured 6-keto-PGFlα (stabile metabolite of PGI₂), TXB₂ (stabile metabolite of thromboxane A₂) active renin, and arginine vasopressin (AVP) plasma concentrations by radioimmunoassay. Catecholamine levels were assessed by high-pressure liquid chromatography (HPLC) with electrochemical detection. Results : Following MT, arterial hypotension occurred along with a substantial PGI₂ release. This was completely abolished by ibuprofen administration. Although plasma levels of 6-keto-PGF_1α (1133 (708) vs. 60 (3) ng/L, median (median absolute deviation), P=0.0001, placebo vs. ibuprofen) remained significantly elevated, blood pressure was restored within 30 min after MT in the placebo group. At the same point in time plasma concentrations of TXB² (164 (87) vs. 58 (1) ng/L, P=0.0001), epinephrine (46 (33) vs. 14 (6) ng/L, P=0.001), AVP (41 ± (18) vs. 12 (7) ng/L, P=0.0004), and active renin (27 (12) vs. 12 (4) ng/L, P = 0.001) were significantly higher in placebo-treated patients. Conclusion : Under combined general and epidural anesthesia arterial hypotension following MT due to endogenous PGI₂ release is associated with enhanced release of AVP, active renin, epinephrine and thromboxane A₂, presumably contributing to hemodynamic stability within 30 min after MT.     

A Teaspoon Pump for Pumping Blood with High Hydraulic Efficiency and Low Hemolysis Potential

Abstract: Virtually all blood pumps contain some kind of rubbing, sliding, closely moving machinery surfaces that are exposed to the blood being pumped. These valves, internal bearings, magnetic bearing position sensors, and shaft seals cause most of the problems with blood pumps. The original teaspoon pump design prevented the rubbing, sliding machinery surfaces from contacting the blood. However, the hydraulic efficiency was low because the blood was able to "slip around" the rotating impeller so that the blood itself never rotated fast enough to develop adequate pressure. An improved teaspoon blood pump has been designed and tested and has shown acceptable hydraulic performance and low hemolysis potential. The new pump uses a nonrotating "swinging" hose as the pump impeller. The fluid enters the pump through the center of the swinging hose; therefore, there can be no fluid slip between the revolving blood and the revolving impeller. The new pump uses an impeller that is comparable to a flexible garden hose. If the free end of the hose were swung around in a circle like half of a jump rope, the fluid inside the hose would rotate and develop pressure even though the hose impeller itself did not "rotate"; therefore, no rotating shaft seal or internal bearings are required.     

Microspheres Based Detoxification System: A New Method in Convective Blood Purification

Abstract: A variety of protein-bound or hydrophobic substances, accumulating as a result of pathologic conditions such as exogenous or endogenous intoxications, are removed poorly by conventional detoxification methods because of low accessibility (hemodialysis), insufficient adsorption capabilities (hemosorption), low efficiency (peritoneal dialysis), or economic limitations (high-volume plasmapheresis). Combining advantages of existing methods with microspheric technology, a module-based system was designed. Major operating parameters of the latter can be modified to allow for adjustment to individual clinical situations. An extracorporeal blood circuit including a plasmafilter is combined with a secondary high-velocity plasma circuit driven by a centrifugal pump. Different microspheric adsorbers can be combined in one circuit or applied in sequence. Thus, a prolonged treatment can be tailored using specially designed selective adsorber materials. Comparing this system with existing methods (high-flux hemodialysis, molecular adsorbent recycling system), results from our in vitro studies and animal experiments demonstrate the superior efficiency of substance removal.     

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.     

Tissue perfusion in relation to cardiac output during continuous positive-pressure ventilation and administration of propranolol or verapamil

Background : Our objective was to determine whether administration of propranolol or verapamil modifies the hemodynamic adaptation to continuous positive-pressure ventilation (CPPV), in particular the regional distribution of cardiac output (CO).
Methods : General hemodynamics and regional blood flows assessed by microsphere technique (15 (μm) were recorded in 16 anesthetized pigs during spontaneous breathing (SB) and CPPV with 8 cm H₂O end-expiratory pressure (CPPV8) before and after intravenous administration of propranolol (0.3 mg · kg⁻¹ followed by 0.15 mg · kg⁻¹ · h⁻¹, n=8) or verapamil (0.1 mg · kg⁻¹ followed by 0.3 mg · kg⁻¹ · h⁻¹, n=8).
Results : CPPV8 depressed CO by 25% without shifts in its relative distribution with the exception of a noteworthy increase in adrenal perfusion. Propranolol increased arterial blood pressure, and due to a fall in heart rate, CO dropped by 25%. The kidneys and, to a lesser extent, the splanchic region and central nervous system received increased fractions of the remaining CO at the expense of skeletal muscle flow. Similar patterns were seen during SB and CPPV8 such that the combination of propranolol and CPPV8 depressed CO by 50%. The circulatory effects of verapamil were less evident but myocardial perfusion tended to increase.
Conclusions : The combination of propranolol or verapamil with CPPV does not result in any specific hemodynamic interaction in anesthetized pigs, except that the combined effect of propranolol and CPPV may severely reduce CO.     

Volatile anaesthetics reduce adhesion of blood platelets under low-flow conditions in the coronary system of isolated guinea pig hearts

Background : Inhibitory effects of volatile anaesthetics on platelet aggregation have been demonstrated in several studies. However, the influence of volatile anaesthetics on intracoronary platelet adhesion has not been elucidated so far.
Methods : Isolated hearts of guinea pigs were perfused with buffer in the absence or presence of volatile anaesthetics (0.5 and 1 MAC) at constant coronary flow rates of 5 ml/min for 25 min, then 1 ml/min for 30 min and again 5 ml/min for 10 min. Before, during and after low-flow perfusion, a bolus of human platelets was applied into the coronary system. To simulate thrombogenic conditions, 0.3 U/ml human thrombin was infused during low-flow perfusion and reperfusion. The number of platelets sequestered to the endothelium was calculated from the difference between coronary in- and output of platelets. The myocardial production of lactate and consumption of pyruvate and coronary perfusion pressure were also determined.
Results : At a flow rate of 5 ml/min only about 3% of the applied platelets did not emerge from the coronary system, in any group. In contrast, 13.1±1.2% (mean±SEM) of infused platelets became adherent in low-flow perfusion in the control group without anaesthetic. The adherence was reduced with each 1 MAC isoflurane (to 6.2±1.2%), sevoflurane (to 4.4±0.9%) or halothane (to 3.2±1.5%) (each P <0.05 vs. control). Volatile anaesthetic, 0.5 MAC, did not inhibit platelet adhesion to a statistically significant extent in any case. Perfusion pressure and metabolic parameters were not statistically different between the control and the hearts exposed to anaesthetics.
Conclusion : Volatile anaesthetics in a concentration of 1 MAC can reduce the adhesion of platelets in the coronary system under reduced flow conditions. This action does not arise from vasodilation or inhibition of ischaemic stress.     

Bariatric Surgery in Some "Central and East-European (former Eastern bloc)"Countries - Current Status and Prediction for the Next Millennium

Background: Obesity is increasing globallly, including in the formerly "Eastern Bloc" countries. Methods: A survey was made of obesity and bariatric surgery. Results: In the 8 East and Central European countries studied, with total population 300 million, roughly 43% of the population was overweight (BMI 25-30), 23% obese (BMI > 30), with about 15 million people morbidly obese (BMI > 40). From 0-10 morbidly obese individuals/100,000/year undergo bariatric surgery. Conclusion: Most countries were found to provide inadequate treatment for obesity.The majority of the morbidly obese are not treated effectively. However, health-care awareness of obesity and bariatric surgeons are slowly increasing.     

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.     

Influence of dopexamine hydrochloride on haemodynamics and regulators of circulation in patients undergoing major abdominal surgery

Background: Catecholaminergic support is often used to improve haemodynamics in patients undergoing major abdominal surgery. Dopexamine is a synthetic vasoactive catecholamine with beneficial microcirculatory properties. Methods: The influence of perioperative administration of dopexamine on cardiorespiratory data and important regulators of macro- and microcirculation were studied in 30 patients undergoing Whipple pancreaticduodenectomy. The patients received randomized and blinded either 2 μg · kg^?1 · min^?1 of dopexamine (n=15) or placebo (n=15, control group). The infusion was started after induction of anaesthesia and continued until the morning of the first postoperative day. Endothelin-1 (ET-1), vasopressin, atrial natriuretic peptide (ANP), and catecholamine plasma levels were measured from arterial blood samples. Measurements were carried out after induction of anaesthesia, 2 h after onset of surgery, at the end of surgery, 2 h after surgery, and on the morning of the first postoperative day. Results: Cardiac index (CI) increased significantly in the dopexamine group (from 2.61±0.41 to 4.57±0.78 1 · min^?1 · m^?2) and remained elevated until the morning of the first postoperative day. Oxygen delivery index (DO₂I) and oxygen consumption index (VO₂I) were also significantly increased in the dopexamine group (DO₂I: from 416±91 to 717±110 ml/m² · m²; VO₂I: from 98±25 to 157±22 ml/m² · m²), being significantly higher than in the control group. pHi remained stable only in the dopexamine patients, indicating adequate splanchnic perfusion. Vasopressive regulators of circulation increased significantly only in the untreated control patients (vasopressin: from 4.37±1.1 to 35.9±12.1 pg/ml; ET-1: from 2.88±0.91 to 6.91±1.20 pg/ml). Conclusion: Patients undergoing major abdominal surgery may profit from prophylactic perioperative administration of dopexamine hydrochloride in the form of improved haemodynamics and oxygenation as well as beneficial influence on important regulators of organ blood flow.