心肌缺血/再灌注损伤中微小RNA的作用研究进展

背景 心肌缺血/再灌注损伤(ischemia/reperfusion injury,I/RI)是临床最常见的损伤之一,微小RNA(microRNA,miRNA)参与了其进程. 目的 对心肌I/RI过程中miRNA作用的最新进展进行综述. 内容 回顾并展望miRNA在心肌缺血/再灌注中的作用. 趋向 miRNA与心肌I/RI密切相关,更多以miRNA为靶点的治疗会被用于心肌保护.     

挥发性麻醉药对缺血/再灌注肺损伤的保护机制

挥发性麻醉药对肺的作用目前尚有争议,但其抑制炎症反应的效应抗缺血/再灌注(I/R)损伤的保护性效应已在心肌、脑、肝、肾脏中得到证实.现就挥发性麻醉药对肺泡毛细血管的通透性、炎症因子、中性粒细胞的聚集及黏附分子的表达等的影响阐述挥发性麻醉药的肺保护的作用及机制.     

炎症反应在心肌缺血/再灌注损伤中作用的研究进展

背景 心肌缺血/再灌注损伤(ischemia/reperfusion injury,I/RI)是指在缺血心肌恢复血流灌注后,细胞代谢功能障碍和结构破坏反而加重的现象,并且伴随有以炎症细胞浸润和细胞因子产生为特征的炎症反应.目前认为,炎症反应是I/RI的重要病理机制之一,再灌注诱发的炎症反应及其介质可加重心肌I/RI,而...     

miRNA在缺血预处理保护心肌缺血/再灌注损伤中的研究进展

背景microRNAs(miRNAs)是一类由动物、 植物和病毒基因组编码的约由22个核苷酸组成的小分子单链RNA.近年来发现它在缺血预处理(ischemic preconditioning,IPC)中发挥着重要作用,有望成为研究治疗心肌缺血/再灌注损伤(ischemia/reperfusion injury,I/RI)的新靶点.目的 阐述不同miRNA在IPC保护心肌I/RI中的作用及其可能机制.内容IPC是经典的保护心肌I/RI的方法,IPC后心肌中miRNA表达谱发生改变,其中miR-1、miR-21、miR-133b-5p、miR-199a、miR-144/451可能通过不同的基因调节机制影响IPC保护心肌I/RI.趋向将miRNA与靶基因、 信号调节通路相结合将是未来研究miRNA调节IPC保护心肌I/RI的重要趋势.     

微小RNA与心肌缺血/再灌注损伤研究进展

背景 近年研究表明微小RNA(microRNA,miR)参与了心肌缺血/再灌注损伤(ischemia/reperfusion injury,I/RI)的进程. 目的 综述miR参与心肌I/RI的研究进展. 内容 概述miR及与心肌I/RI有关的miR的作用,并作展望.趋势 miR与心肌I/RI密切相关.以miR为靶点的治疗将可能被用于心肌保护.     

转录因子NF-E2相关因子2-氧化反应元件通路在抗心肌再灌注损伤中的作用

背景 转录因子NF-E2相关因子2(Nf-E2 related factor-2,Nrf2)抗氧化反应元件(antioxidant response element,ARE)通路广泛分布于机体心血管系统中,激活后可上调内源性抗氧化系统减轻心肌的氧化损伤. 目的 阐述Nrf2-ARE通路作为抗心肌缺血/再灌注损伤(ischemia/reperfusion injury,I/RI)的潜在靶点,并探讨其可能的保护机制.内容 Nrf2-ARE通路处于氧化应激、炎症反应的中心地位,介导编码抗氧化蛋白和二项解毒酶基因的基础表达和诱导表达;多种外源性化合物可以激活Nrf2-ARE通路,在转录水平上调节抗氧化蛋白及二项解毒酶基因的表达,增强内源性抗氧化系统的能力从而在减少氧自由基产生、抗炎症反应、减轻钙超载、抗心肌细胞凋亡等方面减轻心肌I/RI.趋向 激活Nrf2-A RE通路可为临床抗I/RI提供新的策略.     

心肌缺血/再灌注损伤治疗新策略——迷走神经电刺激

背景 虽然缺血预处理(ischemic precondition,IPC)仍然是目前已知的最强大内源性心肌保护措施,但是因时机选择等原因其临床应用受到了极大的限制.大量动物实验证明,刺激迷走神经能够通过激活“胆碱能抗炎通路”、降低心肌交感神经兴奋性和抑制氧自由基的产生等作用机制,来减轻心肌缺血/再灌注损伤(ischemia/reperfusion injury,I/RI).另外,也有少数随机对照临床研究证实了迷走神经刺激的心肌保护作用.目的 评价迷走神经刺激对心肌I/RI的保护作用.内容 包括迷走神经刺激的发现、发展,心肌保护作用的机制及其临床应用价值. 趋向 这一现象的发现为降低心肌I/RI提供了一个简单易行且费用低廉的措施.然而,在将迷走神经刺激推荐作为临床工作的常规措施之前,仍需进行更多大规模的临床研究,以评估和优化迷走神经刺激措施的保护作用.     

热休克蛋白在缺血后处理器官保护中的作用

背景 缺血后处理(ischemic postconditioning,IPo)减轻器官缺血/再灌注损伤(ischemia/reperfusion injury,I/RI)的效果确切,临床实用性强,成为近年来的研究热点.热休克蛋白(heat shock protein,HSP)是细胞应激反应的生物学标志及内源性保护蛋白,参与器官I/RI过程.目的 总结国内外对IPo与HSP在器官I/RI中作用的研究成果,为IPo器官保护机制的研究提供思路.内容 国内外学者研究证实IPo可以减轻多种器官的I/RI,并将其应用于临床,取得一定的疗效.HSP通过减轻再灌注过程中的氧化应激反应和炎症反应,减少细胞凋亡,保护细胞骨架的完整性,发挥细胞保护作用.趋势 IPo器官保护作用的机制研究应成为广大学者今后的研究方向,与其为临床应用提供理论基础.     

心肌缺血/再灌注损伤中细胞胀亡产生机制的研究进展

背景 细胞胀亡和凋亡均可出现在心肌缺血/再灌注损伤(ischemia/reperfusion injury,I/RI)过程中.胀亡是一种特殊形式的非凋亡性细胞死亡方式,它的特征表现为细胞肿胀、起泡、细胞器肿胀、细胞膜通透性增加和核溶解. 目的 明确细胞胀亡在心肌缺血/再灌注(ischemia/reperfusion,I/R)发生、发展中的作用将有助于心肌保护研究的深入. 内容 阐述细胞胀亡的生物学特性、发生机制及与心肌I/RI. 趋向 通过对心肌I/RI中细胞胀亡的深入了解和研究,有可能带来心肌保护的新突破.     

亲环素在缺血/再灌注炎症性损伤中作用的研究进展

背景 亲环素(cyclophilin,Cyp)是一类具有肽基脯氨酰顺反异构酶活性的蛋白质家族,研究表明Cyp在心肌缺血/再灌注损伤(Ischemia/reperfusion injury,I/RI)过程中发挥着重要作用.目的 分析总结有关Cyp参与I/RI发生机制的文献资料.内容 简要描述Cyp家族的分子结构及生物学功能,重点阐述CypA在缺血/再灌注炎症性损伤过程中的作用机制.趋向 Cyp有可能成为防治心肌I/RI的一个新靶点,新型无免疫抑制作用的Cyp配体具有十分广阔的治疗前景.     

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.