Pim-1在胃癌组织中的表达及其临床意义

探讨Pim-1在胃癌组织中的表达及其临床意义。收集2014年10月—2015年11月手术切除的胃癌石蜡标本和癌旁组织59例。采用实时荧光定量技术(RT-PCR)检测胃癌组织和癌旁组织中Pim-1、VEGF-A mRNA的表达情况。胃癌组织Pim-1、VEGF-A mRNA水平高于癌旁组织,差异有统计学意义(t=20.05,17.39,P=0.000,0.000)。随着TNM分期的增加和分化程度的降低,胃癌组织Pim-1、VEGF-A mRNA水平呈升高趋势(P0.05)。出现远处转移和淋巴结转移者的胃癌组织Pim-1、VEGF-A mRNA水平高于未出现远处转移和淋巴结转移者(P0.05)。胃癌组织中Pim-1、VEGF-A mRNA水平呈正相关(r=0.402,P=0.012)。胃癌组织中Pim-1、VEGF-A的表达高于癌旁组织。Pim-1、VEGF-A的表达与胃癌的病理及预后密切相关,Pim-1、VEGF-A可能共同在胃癌发病中起作用。     

CD24在胃癌中的表达及其临床意义

目的检测CD24mRNA和蛋白在胃癌原发灶、癌旁黏膜及区域淋巴结中的表达情况．并探讨其表达与胃癌临床病理特征及预后的关系。方法对收集的55例胃癌患者的标本．采用RT-PCR和免疫组织化学染色的方法．检测CD24在胃癌原发灶、癌旁黏膜及区域淋巴结中的表达情况．并分析CD24的表达情况与患者临床病理特征及预后之间的关系。结果胃癌中CD24mRNA和蛋白的表达均高于癌旁黏膜（P〈0．05）：转移淋巴结中CD24mRNA和蛋白的表达均高于未转移淋巴结（P〈0．05）。除男性患者CD24的表达高于女性患者（P〈0．05）．CD24的表达与其他临床病理特征及预后之间并无相关性（均P〉0．05）。结论CD24的高表达可能在胃癌的发生和转移中具有重要作用。     

Bmi-1在胃癌中的表达及其意义

目的 探讨Bmi-1在胃癌组织中的表达及其与临床病理因素之间的关系.方法 采用RT-PCR和Western blot技术检测44例胃癌组织和癌旁正常组织中Bmi-1的表达.结果 胃癌组织Bmi-1mRNA阳性表达率为72.73％,显著高于癌旁正常组织(13.64％)(P＜0.05);Bmi-1蛋白在胃癌组织中表达显著高于癌旁正常组织(P＜0.05);在有淋巴结转移以及远处转移的患者中Bmi-1的表达显著高于无淋巴结转移和无远处转移阴性患者(P＜0.05).但Bmi-1的表达与患者的性别、年龄、肿瘤大小及分化程度无关,该4因素的分组间差异无统计学意义(P＞0.05).结论 Bmi-1的表达上升可能与胃癌的发生及浸润、转移有关.     

MMP-9和CD105在胃癌及正常胃黏膜组织中的表达及意义

探讨基质金属蛋白酶-9(MMP-9)及新生血管标志物CD105在胃癌及正常胃黏膜组织中的表达及其临床意义。选取病理科存档的胃癌患者术后组织蜡块,其中胃癌组织54例、癌旁组织37例(距离癌组织>3 cm)、正常胃黏膜组织20例,采用免疫组织化学法检测3种组织标本中的MMP-9、CD105表达情况,并分析两者与胃癌的临床病理特征的关系。胃癌组织中的MMP-9阳性表达率72.22%,显著高于癌旁组织(29.73%)和正常胃黏膜组织(5.00%,P<0.05),胃癌组织中MVD计数(43.7±8.9)个/视野,显著多于癌旁组织和正常胃黏膜组织(P<0.05)。胃癌组织中的MMP-9阳性表达与胃癌的分化程度、淋巴结转移、浸润深度、TNM分期有关(P<0.05);胃癌组织中的MVD在胃癌低分化、淋巴结转移、浆膜及浆膜下层浸润、Ⅲ+Ⅳ分期中计数显著增高(P<0.05)。MMP-9及CD105表达变化可以鉴别诊断胃癌,同时有利于对胃癌的临床病理特征、恶性程度进行评估。     

Eph受体酪氨酸激酶A2和CD133在胃癌组织的表达及其与胃癌发生发展的关系

目的 探讨Eph受体酪氨酸激酶A2(EphA2)和CD133在胃癌组织中的表达及其与临床病理特征和预后关系.方法 采用免疫组织化学法检测82例胃癌患者手术切除的癌组织和癌旁组织中EphA2和CD133表达水平.结果 EphA2在胃癌组织中的表达率明显高于癌旁组织(86.59％比20.73％,P＜0.01),CD133在胃癌组织中的表达率明显高于癌旁组织(67.07％比10.98％,P＜0.01);EphA2表达水平与胃癌TNM分期、淋巴结转移明显相关(P＜0.05),CD133表达水平与胃癌组织学分化程度、TNM分期、淋巴结转移明显相关(P＜0.05).结论 EphA2和CD133过度表达可能在胃癌的发生、发展过程中发挥作用.     

抑癌基因Lumican在胃癌中的表达及其临床意义

目的探讨抑癌基因Lumican mRNA在胃癌组织中的表达及其在胃癌发生、发展中的意义。方法采用逆转录聚合酶链反应(RT-PCR)方法检测66例胃癌组织及其相应的近癌旁组织及正常组织中LumicanmRNA的表达,并分析胃癌组织中Lumican mRNA表达与其临床病理特征的关系。结果Lumican mRNA在胃癌组织、近癌旁组织及正常组织中的表达缺失率分别为42.4%(28/66)、15.2%(10/66)及0(0/66)。有淋巴结转移者胃癌组织中Lumican mRNA表达缺失率(61.1%)明显高于无淋巴结转移者(20.0%),差异有统计学意义(χ2=11.323,P=0.001);晚期(Ⅲ、Ⅳ期)胃癌组织中Lumican mRNA表达缺失率(61.5%)明显高于早期(Ⅰ、Ⅱ期,30.0%),差异有统计学意义(χ2=6.417,P=0.011;胃癌组织中Lumican mRNA表达缺失与肿瘤分化程度无关(χ2=1.576,P=0.455)。结论Lumican mRNA表达缺失可能在胃癌的发生和发展过程中起重要作用,并影响其预后。     

人胃癌组织中肝素酶基因启动子甲基化状态与肿瘤侵袭转移的关系

目的 探讨人胃癌组织中肝素酶(HPA)基因启动子的甲基化状态及其与HPA表达、肿瘤侵袭转移的关系.方法 应用免疫组织化学、逆转录-聚合酶链反应(RT-PCR)方法检测48例胃癌组织标本及相应癌旁组织中HPA蛋白和mRNA表达;采用亚硫酸氢钠修饰、甲基化PCR(MSP)、甲基化克降测序(BSP)法检测胃癌组织和癌旁组织中HPA基因启动子区域CpG岛甲基化状态,并探讨与胃癌临床病理特征的关系.结果 胃癌组织中HPA mRNA和蛋白的阳性表达率分别为79.20%(38/48)、93.75%(45/48),显著高于癌旁组织(P<0.05).MSP、BSP检测发现13例胃癌组织HPA启动子CpG岛呈低甲基化状态,且其甲基化程度与HPA的表达及胃癌的分化程度、TNM分期、淋巴结转移、远处转移明显相关(P<0.05).结论 HPA基因启动子区域CpG岛甲基化程度与HPA的表达及胃癌的发生、发展有关,在肿瘤侵袭、转移过程中起重要调节作用.     

胃癌组织中CD133的表达及其临床意义

目的研究胃癌组织中CD133表达的相互关系,重点明确术前、术后外周血单核细胞中CD133mRNA表达的临床意义及其与胃癌原发灶CD133表达的关系。方法 50例胃癌、10例胃溃疡穿孔及10名健康自愿者入组研究。胃癌患者术前和术后1周抽外周静脉血各4 ml,密度梯度离心法分离单核细胞,半定量逆转录聚合酶链反应(RT-PCR)检测CD133 mRNA表达水平。胃溃疡穿孔患者术前抽外周静脉血、健康自愿者抽晨血各4 ml。胃癌原发灶及癌旁正常胃黏膜组织分别行RT-PCR、免疫组织化学染色检测CD133 mRNA和蛋白的表达。分析CD133表达对各临床病理特征和预后的影响。结果健康自愿者及术前胃溃疡患者及胃癌患者外周血中CD133 mRNA的半定量值分别为0.029±0.060、0.059±0.099及0.270±0.163(P=0.000)。胃癌患者术前外周血CD133 mRNA表达与肿瘤组织分化程度、淋巴管浸润、肿瘤浸润深度、淋巴结转移及TNM分期均有关(P<0.05)。相关分析显示,胃癌患者术前外周血中CD133 mRNA半定量值与淋巴结转移率(rs=0.422,P=0.002)、癌转移淋巴结枚数(rs=0.398,P=0.004)呈正相关,并与胃癌原发灶中CD133 mRNA的表达呈正相关(rs=0.337,P=0.017)。胃癌原发灶中CD133蛋白表达阳性者,术前外周血中CD133 mRNA的半定量值较CD133蛋白表达阴性者高(Z=-2.539,P=0.011)。50例胃癌患者行胃癌根治术后1周,其外周血中CD133 mRNA半定量值明显高于术前CD133 mRNA的表达水平(P=0.021)。胃癌浸润深度较深者,术后CD133 mRNA表达升高更明显(Z=-1.978,P=0.039)。术后外周血中CD133 mRNA高表达者较低表达者预后更差(χ2=6.193,P=0.013)。结论胃癌患者术前外周血高表达CD133 mRNA,其与肿瘤分化程度、淋巴管浸润、肿瘤浸润深度、淋巴结转移、TNM分期及胃癌原发病灶CD133蛋白表达有关,且与淋巴结转移率、癌转移淋巴结枚数及胃癌原发灶中CD133 mRNA的表达呈正相关。术后患者外周血中CD133 mRNA半定量值较术前明显升高,这一升高提示肿瘤浸润程度较深,患者预后较差。     

DEC1和STAT3在胃癌组织中的表达及意义

目的:探讨DECl和S1-AT3在胃癌组织中的表达及其在胃癌发病机制中的作用.方法:利用免疫组织匕学方法检测59例胃癌组织中DEC1、STAr3 2种蛋白的表达情况,以19例癌旁正常组织作为对照.结果:DECl蛋白在胃癌组织中的阳性表达率为71.2%,高于癌旁正常组织的阳性表达率(26.3%.P<0.05).胃癌组织中的DECl表达与STAT3表达呈正相关,与肿瘤的分化程度有关,但与患者性别、年龄、肿瘤大小、TNM分期、浸润深度、有无淋巴结转移及远处转移无关;STAT3蛋白的表达与肿瘤的TNM分期、分化程度、浸润深度、淋巴结转移有关,而与患者性别、年龄、肿瘤大小及远处转移无关.结论:DEC1蛋白在胃癌组织中高表达,且与STAT3蛋白的表达相关.DECl和STAT3均为转录调节因子,二者的相互调节很可能在胃癌的发生发展中具有重要作用.     

miR-153在胃癌组织中的表达及其临床意义

目的:探讨miR-153在胃癌中的表达及其临床意义。方法:收集49例胃癌根治术后组织和配对癌旁正常组织标本,采用实时荧光定量-聚合酶链反应(RT-qPCR)检测miR-153的表达水平,并分析其与胃癌临床TNM分期、肿瘤大小、分化程度、淋巴结转移等临床病理参数之间的关系。结果:miR-153在胃癌组织中的表达量显著低于相应癌旁正常组织(P0.01),miR-153的表达量与胃癌淋巴结转移有关(P0.05),与民族、性别、年龄、分化程度、肿瘤大小、临床TNM分期等病理参数无关(P0.05)。结论:miR-153在胃癌组织中低表达,提示miR-153可能与胃癌的发生发展有关。     

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 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.     

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.     

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.