缝隙连接蛋白43与心肌缺血／再灌注损伤机制的研究进展

背景研究表明,心肌缺血／再灌注（ischemia／reperfusion,I／R）损伤的发病机制与氧自由基过量产生、钙超载、线粒体损伤及心肌细胞凋亡等密切相关,最新研究发现缝隙连接（gapjunction,GJ）也参与心肌I／R损伤。目的现主要针对GJ连接蛋白（connexin,Cx）43与心肌I／R损伤的关系作一综述。内容Cx43在心肌I／R损伤中参与心肌保护作用,其机制可能与钙超载、在线粒体中的分布及细胞凋亡等因素相关。趋向未来研究需要进一步探究Cx43与心肌细胞凋亡之间的关系,同时为临床实际工作提供依据。     

心磷脂与缺血/再灌注损伤

心磷脂（CL）是维持线粒体能量代谢所必需的一种磷脂，参与了众多重要生理过程。此文对CL的结构、合成和转化；在维持线粒体正常功能中的作用；缺血／再灌注（I／R）损伤中的改变以及和线粒体功能的关系等作了逐一阐述，说明CL与I／R损伤导致的细胞死亡关系密切，CL量或性质的改变在细胞凋亡中处于中心地位。     

丁羟茴香醚对衰老大鼠肾脏缺血再灌注损伤的保护作用

目的观察老年大鼠肾脏缺血再灌注（I／R）模型中。肾小管上皮细胞的损伤变化，探讨活性氧（ROS）清除剂对I／R损伤的保护作用。方法27月龄大鼠随机分为假手术组、I／R模型组、丁羟茴香醚（BHA）组和nicardipine组。夹闭双侧。肾动脉30min再灌注18h制成I／R模型。观察肾功能、肾脏病理改变、肾小管上皮细胞凋亡情况。检测肾组织半胱氨酸天冬氨酸蛋白酶（caspase）3、细胞色素C表达。测定肾组织脂质过氧化物丙二醛（MDA）含量和超氧化物歧化酶（SOD）活性。结果（1）肾脏I／R损伤时，老年大鼠肾功能明显减退，肾组织病理改变比较明显，大量肾小管上皮细胞凋亡，肾组织caspase-3、细胞色素C表达明显上调。肾组织中MDA增加、SOD活性下降（P均〈0．05）。（2）BHA或nicardipine均能明显改善肾功能。肾组织病理改变和凋亡相关指标（P〈0．05）；BHA或nicardipine均能减少组织中MDA含量，部分恢复肾组织中SOD含量。结论老年大鼠肾脏I／R损伤时肾小管上皮细胞凋亡增加，肾功能减退。ROS堆积后，线粒体损伤导致肾小管上皮细胞凋亡。清除ROS可以抑制‘肾小管上皮细胞凋亡，减轻I／R损伤。     

活性氧对兔肝癌组织的作用

目的研究活性氧对肝癌缺血再灌注（I／R）后的损伤作用。方法建立兔肝脏肿瘤模型，并于肝缺血再灌注和经门静脉穿刺一次性灌注高氧液（氧分压为80kPa）5mL后1h，1d，3d和7d各时点分别取肿瘤组织和肝脏组织，测定超氧化物歧化酶（SOD）和过氧化氢酶（CAT）的含量。用TUNEL染色法观察组织的细胞凋亡情况。结果单纯I／R后正常肝组织和肝癌组织中的SOD浓度均有明显下降，正常肝脏组织CAT浓度均有所升高，肝癌组织中于再灌注1d CAT浓度显著降低并达最低水平。恢复血流同时经门静脉灌注高氧液后，正常肝组织及肝癌组织中SOD浓度均较I／R各个时点明显降低，但再灌注7d时仍低于再灌注前。两种组织中的CAT浓度于I／R1h下降达最低，但从再灌注3d以后，正常肝组织中的CAT浓度回升至正常水平，而再灌注7d时肝癌组织中的CAT浓度仍处于较低水平。I／R后正常肝组织和肝癌组织的凋亡细胞增多，肝癌组织中细胞凋亡在灌注高氧液后1d和3d最为显著。I／R和灌注高氧液后，肝癌组织中SOD和CAT的浓度和凋亡细胞改变均较正常肝组织显著（P〈0．01）。结论经门静脉灌注高氧液可加强I／R对肝癌组织的氧化改变和损伤，而对正常肝脏组织的影响较小。     

大鼠肝脏缺血再灌注损伤程度判定指标的选择

目的 探讨肝脏缺血再灌注（I／R）损伤程度及其判断指标的选择。方法 建立大鼠肝脏局部I／R模型，测定大鼠肝脏缺血60，90min再灌注0，1，2，4，6，12，24，48h时的血清丙氨酸转氨酶（ALT）水平，并行病理检查（相对细胞死亡率）。参照本院I／R损伤分级标准重新将动物分为4个不同的I／R损伤程度的实验组，分析ALT水平与病理改变的关系。结果 缺血60min组中轻度I／R损伤占75．0％，中度I／R损伤占14．6％，重度I／R损伤占10．4％；缺血90min组中轻度I／R损伤占41．7％，中度I／R损伤占25．0％，重度I／R损伤占16．7％，严重度I／R损伤占16．7％。损伤程度越重细胞死亡率越高，ALT水平也越高。结论 ALT水平可直接反映肝脏I／R损伤程度；损伤程度越重，转氨酶水平越高，细胞死亡率也越高。     

乌司他汀对肝脏缺血再灌注损伤的防护作用

目的 探讨肝脏缺血再灌注(I/R)损伤的发生机制，观察乌司他汀(UTI)对肝脏I／R损伤的保护作用。方法 选择外伤性肝破裂手术中行肝门阻断术患者38例，随机分为I／R组和UTI组各19例。观察肝脏I／R后血清TNF、MDA、AST、ALT变化及再灌注肝组织多形核白细胞(PMN)浸润和肝组织形态学变化。结果 I／R组：血清TNF、MDA、AST、ALT显著升高，肝组织PMN浸润明显增加。电镜下可见肝窦内皮细胞破坏，肝细胞线粒体结构改变。UTI组：血清TNF、MDA、AST、ALT明显降低。肝组织PMN浸润明显减少，肝组织超微结构明显改善。结论肝脏I／R诱导TNF产生。UTI能明显减轻PMN依赖性肝脏I／R损伤。     

缺血-再灌注损伤对大鼠急性胰腺炎胰腺细胞凋亡的影响

目的探讨缺血一再灌注(I／R)损伤对大鼠急性胰腺炎(AP)胰腺细胞凋亡的影响。方法将SD大鼠54只按编号法随机分为对照组(n=6)、胰腺炎组(n=24)和I／R损伤组(n=24)。经胆胰管逆行加压注入3％牛磺胆酸钠建立大鼠AP模型，在此基础上，I／R损伤组通过暂时阻断脾下动脉造成局部胰腺I／R模型，对照组于术后lh，其余两组于术后1h、3h、6h和12h采取断颈方法分批处死动物，应用末端脱氧核苷酸转换酶(TdT)介导的原位末端标记(TUNEL)法检测缺血一再灌注区胰腺细胞凋亡。并观察其病理改变。结果胰腺炎组大鼠术后1h、3h胰腺组织仅为充血、水肿性改变，6h出现出血、坏死性改变；而1／R损伤组大鼠术后1h缺血一再灌注区胰腺呈现出血、坏死性改变，病变持续加重；AP后胰腺凋亡细胞明显增多，I／R损伤组和胰腺炎组的凋亡细胞高峰值分别在术后3h和6h；I／R损伤组术后1h、3h缺血一再灌注区胰腺凋亡细胞显著高于相应时相的胰腺炎组(P＜0．01，P＜0．05)．而6h、12h明显低于胰腺炎组(P＜O．05，P＜O．01)。结论I／R损伤在促发胰腺炎从水肿型向出血坏死型转化过程中，同时诱导胰腺细胞凋亡，细胞凋亡可能是阻止AP病变加重的一个有利反应。     

依达拉奉对大鼠肝脏缺血再灌注时线粒体膜电位的影响

目的 探讨依达拉奉对大鼠肝脏缺血再灌注时线粒体膜电位的影响.方法 成年健康雄性SD大鼠30只,体重250 ～ 300 g,采用随机数字表法,将其随机分为3组(n=10):假手术组(S组)、缺血再灌注组(I/R组)及依达拉奉组(E组),I/R组和E组采用肝脏缺血60 min进行再灌注的方法制备70％肝脏缺血再灌注损伤模型.E组于再灌注前15 min静脉注射依达拉奉3 mg/kg,I/R组给予等容量生理盐水.于再灌注2h时采集静脉血样,测定血清谷丙转氨酶(ALT)和谷草转氨酶(AST)的活性;然后处死大鼠,取肝组织,测定肝细胞凋亡情况,计算肝细胞凋亡指数;制备肝组织单细胞悬液,测定线粒体膜电位;光镜下观察肝组织病理学结果.结果 与S组比较,I/R组及E组血清ALT活性、AST活性和肝细胞凋亡指数升高,线粒体膜电位降低(P＜0.05或0.01);与I/R组比较,E组血清ALT活性、AST活性和肝细胞凋亡指数降低,线粒体膜电位升高(P＜0.05).E组肝组织病理学损伤轻于I/R组.结论 依达拉奉可减轻大鼠肝脏缺血再灌注损伤,其机制与升高线粒体膜电位,抑制肝细胞凋亡有关.     

补体和肾缺血再灌注损伤

肾缺血再灌注(ischemia/reperfusion，I／R)损伤是导致急性肾衰竭(acute renal failure，ARF)最常见的原因。补体系统通过促进炎性细胞的浸润和凋亡在肾I／R损伤中发挥着重要作用。利用特异的补体抑制剂抑制补体活化可能产生有效的肾脏保护作用。     

肠缺血／再灌注损伤与防治措施

背景肠缺血／再灌（ischemia／reperfusion,I／R）损伤是外科实践中常见的组织器官损伤之一,在严重感染、创伤、休克、心肺功能不全等疾病的病理生理演变过程中起重要作用。目的就肠I／R损伤产生机制以及防治措施的研究进展进行综述,为今后临床工作提供指导。内容针对肠I／R损伤机制（氧自由基、能量缺乏、细胞内Ca^2＋超载、炎症反应、细胞异常凋亡）及其防御措施的研究进展展开论述。趋向肠I／R损伤是综合性原因引起,采取综合性防治措施可防治肠I／R损伤。     

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.     

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.     

Immunomodulation in Transplantation with Photopheresis

Abstract: Photopheresis is a technique in which peripheral blood mononuclear cells, in the presence of a photoacti-vatable compound, are exposed extracorporeally to ultraviolet A light and reinfused, inducing a host autoregula-tory immune response. Experimental work and ongoing clinical studies are helping to define the role of this novel, safe, and non-toxic immunomodulating technology in the field of transplantation.