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.     

阿片类药物减轻急性缺血/再灌注损伤及相关机制

背景 缺血预处理对于器官缺血/再灌注损伤（ischemia/reperfusion injury,I/RI）具有强大的保护作用,但其临床应用受到时机以及伦理学的限制.近年来有研究发现阿片类药物预处理以及后处理对组织器官I/RI同样具有保护作用,其既不损伤器官又能产生与缺血预处理相同的效果,是更为可行的治疗措施. 目的 在将阿片类药物处理推广至临床应用前,仍需进行更多大规模的临床研究.拟就阿片类处理减轻I/RI的发展过程及其作用机制进行探讨. 内容 阿片类药物处理I/RI的几种方式及其机制. 趋向 阿片类药物处理比较其他损伤性处理方式更易操作,且对I/RI同样具有保护作用,有望成为日后治疗的热点之一.     

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...     

肢体远隔缺血预处理对肝脏缺血/再灌注损伤保护作用的研究进展

背景 肝脏缺血/再灌注损伤(ischemic/reperfusion injury,I/RI)是影响临床肝脏手术和肝脏移植手术术后发病率和病死率的主要因素,肢体远隔缺血预处理(limb remote ischemic preconditioning,LRIPC)可以减轻肝脏I/RI.目的 综述LRIPC对肝脏I/RI保护作用的研究进展.内容 LRIPC的发展、保护作用的机制、保护作用的时相及LRIPC的建模方法.趋向 LRIPC应用于临床防治肝脏I/RI不失为一种可取的方案.     

肢体缺血预处理减轻肝缺血/再灌注损伤的研究进展

背景 肝缺血/再灌注损伤(hepatic ischemia/reperfusion injury,HI/RI)是肝外科手术及肝移植中常见的病理生理现象,是术后肝功能衰竭和移植物无功能的主要原因.研究表明肢体缺血预处理(limb ischemia preconditioning,LIPC)可减轻HI/RI,具体机制仍不清楚.目的 通过综述LIPC减轻HI/R1的可能机制,为临床减轻HI/RI提供新的思路.内容 介绍HI/RI机制及LIPC减轻HI/RI的可能作用机制.趋向 LIPC作为减轻HI/RI的措施具有重大的临床应用价值.     

右美托咪定治疗缺血/再灌注损伤研究进展

背景 右美托咪定(dexmedetomidine,Dex)是新一代α2受体激动药,广泛应用于临床麻醉、重症监护及术后镇静,对部分器官的缺血性损伤有保护作用. 目的 总结Dex治疗缺血/再灌注损伤(ischemia/reperfusion injury,I/RI)的研究进展,为临床及科研提供参考. 内容 Dex在一些重要的器官和组织(小肠、心脏、肾、肺和肝)I/RI中表现出保护作用,机制与其调节基因表达、离子通道激活、递质释放、炎症过程以及细胞凋亡和坏死有关. 趋向 Dex有望成为治疗I/RI的一个选择.     

瑞芬太尼对缺血/再灌注损伤保护作用及可能机制的研究进展

背景 瑞芬太尼是一种新型的阿片受体激动剂,具有独特的快速起效和快速清除的优点,是麻醉过程中常用的镇痛药物.近来,发现瑞芬太尼对重要器官的缺血/再灌注损伤(ischemia/reperfusion injury,I/RI)具有保护作用. 目的 回顾瑞芬太尼的基本理化特点及药代学特点,并讨论其对I/RI的保护作用和可能的作用机制. 内容 大量研究表明瑞芬太尼对心脏、肝脏、神经系统和肾脏的I/RI均有保护作用.其作用机制尚未明了,可能与阿片受体、蛋白激酶C与ATP敏感性钾离子通道、一氧化氮与一氧化氮合酶、抗凋亡通道等有关. 趋向 瑞芬太尼对于I/RI的保护作用,将进一步增加其临床应用价值,也为围术期器官保护提供新的思路.     

七氟醚对肺缺血／再灌注损伤的保护机制

背景七氟醚作为一种较理想的吸入麻醉药,被广泛应用于临床,实验表明七氟醚对肺缺血／再灌注损伤（ischemia／reperfusion injury,I／RI）具有保护作用。目的通过分析近年的研究总结七氟醚对肺I／RI的保护机制。内容七氟醚通过减轻肺通透性、抑制炎症反应、减轻脂质过氧化反应、抑制细胞凋亡、减轻细胞内钙离子超载等发挥肺I／RI的保护作用。趋势应进一步探讨七氟醚对肺的保护作用,加强对七氟醚的临床应用研究,为实际临床工作提供可靠的依据。     

缺血后处理与线粒体通透性转运孔

背景 缺血后处理(ischemic postconditioning,IPo)能明显减轻器官缺血/再灌注损伤(ischemia/reperfusion injury,I/RI),动物实验和临床研究均已经得到证实,其机制可能与增强组织抗氧化能力和抑制细胞凋亡有关.然而近些年提出线粒体通透性转换孔(mitochondria...     

脂多糖预处理减轻机体缺血再灌注损害机制的研究进展

内毒素耐受(ET)是指预先给予小剂量内毒素刺激后机体产生的一系列复杂的适应性调节反应,不仅可防止再次内毒素刺激后机体出现过度的炎症反应,还能诱导对缺血再灌注损害(I/RI)的交叉耐受作用。但由于内毒素临床应用的安全性尚有待评估,同时在面临I/RI的手术前数天给予内毒素预处理以期诱导ET也并不现实,因此,如能阐明ET的发生机制及关键性调控因子,将有可能为以ET为基础的I/RI的治疗找到现实的治疗靶点。     

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.     

A comparison of the inhibitory effects of four volatile anaesthetics on the metabolism of chlorzoxazone, a substrate for CYP2E1, in rabbits

Background: Halothane inhibits in vitro and in vivo activity of cytochrome P-450 (CYP) 2E1. There are several fluorinated volatile anaesthetics besides halothane, and most of them are defluorinated by CYP2E1. It is unclear whether other fluorinated anaesthetics inhibit the in vivo activity of CYP2E1.
Methods: We compared the inhibitory effects of therapeutic concentrations of four inhalational anaesthetics, halothane, enflurane, isoflurane, and sevoflurane, on chlorzoxazone metabolism in rabbits receiving artificial ventilation.
Results: All four inhalational anaesthetics decreased arterial blood pressure and increased plasma chlorzoxazone concentration. However, no significant differences in the plasma chlorzoxazone concentration were found between the four anaesthetics. The estimated chlorzoxazone clearance increased after beginning inhalation with all four agents, but no significant difference in clearance was noted between agents.
Conclusions: At therapeutic concentrations, the in vivo inhibitory effect on chlorzoxazone metabolism was similar for all four inhalational anaesthetics examined, even though their chemical characteristics and extent of hepatic metabolism differ considerably.     

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.     

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.     

Synergistic interaction between the effects of propofol and midazolam with fentanyl on phrenic nerve activity in rabbits

Background: It has been shown that the depressive effects of both propofol and midazolam on consciousness are synergistic with opioids, but the nature of their interactions on other physiological systems, e. g. respiration, has not been fully investigated. The present study examined the effect of propofol and midazolam alone and in combination with fentanyl on phrenic nerve activity (PNA) and whether such interactions are additive or synergistic. Methods: PNA was recorded in 27 anaesthetised and artificially ventilated rabbits. In three groups, propofol, fentanyl and midazolam were administered intravenously in incremental doses to construct dose-response curves for the depressant effects of each one on PNA. In another two groups, the effect of pretreatment with either fentanyl 1 μg · kg^?1 i. v. or midazolam 0.05 mg · kg^?1 i. v. on the effects of propofol and fentanyl respectively on PNA were studied. Results: Propofol and fentanyl caused a dose-dependent depression of PNA with complete abolition at the highest total doses of 16 mg · kg^?1 i. v. and 32 μg · kg^?1 i. v., respectively. In contrast, midazolam in incremental doses to a total of 0.8 mg · kg^?1 reduced mean PNA by 63%, but approximately 12% of PNA remained at a total dose as high as 6.4 mg · kg^?1. The mean ED₅₀s, calculated from dose-response curves, were 5.4 mg · kg^?1, 3.9 μg · kg^?1 and 0.4 mg · kg^?1 for propofol, fentanyl and midazolam, respectively. Initial doses of either fentanyl 1 μg · kg^?1 i. v. or midazolam 0.05 mg · kg^?1 i. v. acted synergistically with subsequent doses of either propofol or fentanyl to abolish PNA at total doses of 8 mg · kg^?1 and 8 μg · kg^?1, respectively. Conclusion: Fentanyl has a synergistic interaction with both propofol and midazolam on PNA and hence potentially on respiration.     

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.