黏着斑激酶对胶质瘤细胞生物学行为的影响

目的探讨反义黏着斑激酶（FAK）对U251人胶质瘤细胞株生物学行为影响。方法以LipofecTAMINE^TM介导的反义FAK寡核苷酸转染U251人胶质瘤细胞株，用Western blot检测胶质瘤细胞株FAK含量的改变，研究其多种细胞生物学行为的变化。结果脂质体介导FAKODN转染率为85．9％。转染反义FAK后，U251人胶质瘤细胞株FAK表达明显减少。U251细胞生长抑制率为64．52％，侵袭细胞下降至21．7个，细胞周期分析显示s期细胞降至25．16％。细胞凋亡率升至34．5％。透射电镜观察到凋亡细胞。结论反义FAK寡核苷酸可显著降低FAK在U251中的表达，降低FAK表达能够显著抑制U251人胶质瘤细胞株侵袭能力，抑制细胞增殖和诱导凋亡。     

莪术醇对人脑胶质瘤U251细胞增生与凋亡影响的实验研究

目的 本研究观察中药活性成分莪术醇对人脑胶质瘤细胞株U251增生与凋亡的影响,检测其对胶质瘤细胞凋亡相关基因表达的影响,初步探讨其抗胶质瘤的可能机制,为脑胶质瘤的中草药治疗积累实验数据.方法 以体外培养的人脑胶质瘤细胞株U251为模型,以培养基稀释莪术醇成不同浓度,观察与检测以下内容:MTT法检测不同时间、不同浓度莪术醇对U251细胞增生的影响;显微镜观察不同浓度莪术醇对U251细胞形态学的影响;流式细胞仪检测不同浓度莪术醇对U251细胞凋亡的影响;RT-PCR法检测不同浓度莪术醇对U251细胞中凋亡相关基因bcl-2与COX-2表达水平的影响.结果 莪术醇对人脑胶质瘤U251细胞增生有抑制效应,且表现出浓度依赖性与时间依赖性(P＜0.05).结论 莪术醇对人脑胶质瘤U251细胞有明确的增生抑制作用.诱导凋亡、抑制增生可能为莪术醇抑制胶质瘤增生效应的重要机制.莪术醇下调人脑胶质瘤U251细胞中bcl-2与COX-2的基因表达水平可能为其诱导凋亡、抑制增生的重要机制之一.     

survivin基因反义寡核苷酸对人肝癌细胞株SMMC-7721细胞凋亡与细胞周期的调控作用

目的研究survivin基因反义寡核苷酸转染对人肝癌细胞株SMMC-7721细胞周期、细胞凋亡的作用及其可能的作用机制。方法采用脂质体介导survivin基因反义寡核苷酸转染人肝癌SMMC-7721细胞,透射电镜观察细胞超微结构,流式细胞术检测细胞周期及细胞凋亡,RT-PCR方法检测cyclin B1 mRNA的表达。结果survivin反义寡核苷酸转染后细胞内cyclin B1表达由0.36±0.03增加至0.91±0.03,同时G2-M期细胞及凋亡细胞比例分别由5.81%及0.7%明显增加至42.11%及31.35%,同时细胞超微结构呈典型凋亡样改变。结论survivin基因反义寡核苷酸转染细胞后可以通过诱导cyclinB1的表达,导致G2-M期阻滞,从而诱导细胞凋亡的发生。survivin基因反义寡核苷酸转染可以作为治疗肝癌的重要新方法。     

导入野生型p53基因对人胶质瘤细胞生长及化疗敏感性的影响

目的 研究野生型p53基因对人胶质瘤细胞生长及化疗敏感性的影响。方法 将载有野生型p53基因的表达质粒PC53-SN3导入U251细胞。通过逆转录-聚合酶链反应(RT-PCR)检测p53基因在转染细胞中的表达,用四甲基偶氮唑盐微量酶反应比色法(MTT法)和流式细胞仪检测p53基因对U251细胞生长抑制及凋亡的影响以及它与顺铂联合作用后的效果。结果 通过RT-PCR证实了野生型p53基因在U251细胞中的表达。MTT检测发现p53基因对U251细胞的生长有明显的抑制作用,抑制率为(79.60±5.69)％。顺铂对 U251细胞的抑制作用随着顺铂浓度的增加(1、2、4、8 mg/L)而增强,抑制率分别为(19.40±6.69)％、(24.41±2.68)％、(51.84±13.38)％、(66.22±5.02)％,但不如 p53基因的抑制作用强。当野生型 p53基因与顺铂联合作用于 U251细胞时,抑制率明显增加,分别为(91.64±1.00)％、(94.98±1.67)％、(95.32±2.01)％、(95.65±1.00)％。p53基因转染所产生的 U251细胞凋亡率为 17.38％。顺铂引起的细胞凋亡率随着顺铂浓度的增加(1、2、4、8mg/L)而增加,分别为5.71％、5.93％、6.27％、6.81％。当p53基因与不同浓度的顺铂(1、2、4、8mg/L)联合作用于U251细胞时,凋亡率也明显增加,分别为23.50％、23.54％、23.89％、28.88％。结论 野生型p53基因与     

反义表皮生长因子受体RNA对U251胶质瘤细胞生长的抑制作用

目的探讨反义靶向表皮生长因子受体（EGFR）在体内外对U251细胞生长抑制作用。方法构建反义EGFR的pcDNA3表达质粒并进行了脂质体介导的U251人脑恶性胶质瘤细胞系基因转染。应用RT-PCR检测EGFR表达水平，应用MTT法、流式细胞术、Matrigel基质生长实验和Transwell方法评价肿瘤细胞转染前后的生物学行为。进一步应用裸鼠皮下荷瘤模型观察脂质体介导反义EGFR基因治疗对U251细胞生长抑制作用。对肿瘤组织应用免疫组织化学的方法进行EGFR、PCNA和GFAP表达比较。结果脂质体介导反义EGFR可显著抑制U251细胞ECFR表达，MTT法分析显示反义EGFR转染组胞生长抑制率为68％；与对照组和pcDNA3转染组比较，细胞周期分析结果表明p-anti-hEGFR转染组G0～G1期细胞数没有明显变化，进入S期的细胞数较对照组减少了，而进入G2期细胞则增加。Matrigel基质生长实验显示对照组和peDNA3转染组细胞呈正常形态贴壁生长。而p-anti-hEGFR转染组细胞不能贴壁生长，呈团块状簇集生长。Transwell方法显示肿瘤细胞的体外侵袭能力显著下降。裸鼠皮下荷瘤模型实验显示反义EGFR RNA可以显著抑制皮下肿瘤生长，组织病理学分析显示治疗组EGFR表达下降而GFAP表达上调。结论反义EGFR可以显著抑制U251细胞的EGFR表达，在体内外对U251细胞生长均产生明显抑制作用。     

Survivin反义寡核苷酸诱导肝癌细胞凋亡及细胞结构的变化

目的采用反义寡核苷酸封闭肝癌细胞中Survivin基因的表达，研究其诱导细胞凋亡过程中对细胞超微结构与细胞骨架的作用及其机理。方法采用脂质体介导Survivin反义寡核苷酸转染人肝癌细胞株SMMC-7721细胞，Western—blot及原位杂交方法检测Survivin蛋白及mRNA表达，流式细胞仪检测细胞凋亡比率，透射电子显微镜观察细胞超微结构变化，激光共聚焦显微镜观察细胞骨架微丝系统变化，激酶活性检测方法测定细胞内Caspase-3活性变化。结果脂质体介导Survivin反义寡核苷酸转染肝癌细胞后Survivin蛋白及mRNA表达分别由69．59及75．60降低至10．71及22．90，Caspase-3活性由0．0153升高至0．0992，同时细胞结构呈典型凋亡改变，细胞内微丝形态结构破坏，细胞凋亡比率由0．7％增加至31．4％。结论脂质体介导转染Survivin反义寡核苷酸可以有效降低细胞内Survivin基因的表达，并激活Caspase-3。活化的Caspase-3可以切割破坏细胞内骨架微丝系统的结构，进而诱导细胞凋亡。     

survivin反义寡核苷酸诱导胃癌原代细胞凋亡的实验研究

目的探讨survivin反义寡核苷酸对人胃癌原代细胞凋亡的影响，为胃癌的靶向治疗提供实验依据。方法利用人胃癌实体瘤新鲜标本培养胃癌原代细胞，胃癌细胞分为空白对照组、脂质体组、正义寡核苷酸组及反义寡核苷酸转染组。用脂质体介导survivin反义寡核苷酸转染胃癌原代细胞，48h后，观察肿瘤细胞的形态变化，Westernblot检测survivin蛋白的表达，流式细胞术检测细胞的凋亡。结果反义寡核苷酸转染组肿瘤细胞体积变小，细胞碎裂，出现凋亡小体；survivin蛋白量下降；流式细胞术检测到肿瘤细胞的凋亡率增高。与其他各组相比，其差异有统计学意义（P〈0．05），而空白对照组、脂质体组、正义寡核苷酸组之间的差异无统计学意义（P〉0．05）。结论survivin反义寡核苷酸在脂质体介导下转染人胃癌原代细胞，可以诱导肿瘤细胞发生凋亡，抑制细胞生长，反义survivin可能成为一个促进胃癌细胞凋亡的手段。     

基因靶向抑制反义生存素对脑胶质瘤细胞增殖和凋亡的影响

目的探讨反义生存素（Survivin）脂质体复合物对脑胶质瘤细胞增殖和凋亡效应的影响及机制，为脑胶质瘤Survivin基因靶向治疗提供理论依据。方法用脂质体介导Survivin反义寡核苷酸转染脑胶质瘤细胞系U251细胞；Western印迹试验检测Survivin表达水平变化；噻唑蓝（MTT）法测量细胞生长情况；流式细胞仪检测细胞凋亡率及线粒体膜电位变化；电镜倒置显微镜观察细胞形态学变化；应用激光共聚焦显微镜免疫荧光分析法评价脂质体反义复合物对Survivin蛋白的影响。结果反义Survivin脂质体复合物能有效下调Survivin表达水平。肿瘤细胞凋亡率随转染时间延长而逐渐递增。并出现凋亡形态学变化。免疫荧光分析中标记有绿色荧光染色的Survivin蛋白分子在未转染的细胞浆中清晰可见。并呈斑点状分布；而在转染细胞中几乎没有发现。结论靶向抑制Survivin基因在脑胶质瘤未来治疗中有良好的应用前景。     

反义p53对创伤后神经元的保护作用

目的 观察p53反义寡核苷酸对创伤后迟发性神经元死亡的防治效果。方法在自由落体打击大鼠弥漫性脑创伤模型中,转染反义寡核苷酸药物,以大鼠神经功能行为评分及Tunel法检测鼠脑皮层神经元DNA损伤情况作为疗效评价指标;用原位杂交、免疫组化法检测p53 mRNA与蛋白质的表达水平。结果大鼠打击后,神经功能行为评分下降,皮层打击区伤后1周内出现神经元凋亡现象。脑创伤后2～4h p53 mRNA及蛋白表达增加。p53反义寡核苷酸转染后的大鼠,神经功能评分明显改善;神经元凋亡数量明显减少;p53 mRNA及蛋白表达减少。结论细胞凋亡在创伤性脑损伤中起重要作用,对创伤后神经功能的缺损有重要影响;反义p53抑制脑创伤后细胞凋亡的发生可能成为治疗创伤性脑损伤后迟发性神经元死亡的新途径。     

肝细胞生长因子受体反义寡核苷酸影响胶质瘤细胞对丝裂霉素C敏感性的研究

目的探讨肝细胞生长因子受体(c-Met)反义寡核苷酸(ASODN)增强胶质瘤细胞系 U251细胞对丝裂霉素C(MMC)敏感性的作用。方法用5 μmol／L c-Met ASODN封闭U251细胞 c-Met mRNA,将50μg/L的MMC与其共培养,采用逆转录-聚合酶链反应(RT-PCR)技术检测c- Met mRNA表达,噻唑蓝(MTT)试验检测U251细胞的生长情况,免疫组织化学法检测细胞PCNA 蛋白的表达,体外检测细胞黏附率。以无义寡核苷酸处理及未处理U251细胞为对照。结果经 c-Met ASODN处理的U251细胞 ,c-Met mRNA的表达(吸光度值为62±21)明显低于经无义寡核苷酸处理U251细胞(吸光度值为150±25,P<0．05);对MMC的敏感性,细胞生长抑制率、细胞黏附率及PCNA指数分别为(53．84±12．21)％、(14．61±3．82)％和(0．35±0．02)％,明显高于相应的无义[(9．86±3．42)％、(24．84±5．90)％和(0．55±0．04)％,P<0．05]。结论 c-Met ASODN能增强胶质瘤细胞系U251细胞对MMC的敏感性,其分子机制可能与c-Met反义寡核苷酸下调了c- Met基因和PCNA蛋白的表达有关。     

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.     

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.     

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.     

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.