胶质瘤中Hedgehog/Gli1信号通路活性变化与血管内皮生长因子表达的关系

目的 探讨胶质瘤中Hedgehog/Gli1信号通路的活化与肿瘤微血管新生之间的关系.方法 54例手术切除的胶质瘤肿瘤标本,免疫组织化学检测胶质瘤组织中Gli与肿瘤微血管密度(MVD)表达的关系;运用Western blot法及定量聚合酶链反应(PCR)检测U87、SHG44、U251及A172胶质瘤细胞中Gli1与血管内皮生长因子(VEGF)在蛋白及mRNA水平的表达;U87、SHG44中通过环巴胺(Cyclopamine)处理胶质瘤细胞束抑制Hedgehog/Gli1信号通路,观察这一信号通路活性下降后对胶质瘤中VEGF表达的影响.结果 随着Hedgehog/Gli1信号通路中Gli1表达数量的增加,MVD也相应地升高;在胶质瘤细胞株U87、SHG44、U251及A172中,U87及SHG44中Hedgehog/Gli1信号通路的活化程度较高,同时VEGF基因及蛋白的表达水平较高;通过Cyclopamine抑制这一信号通路可明显下调胶质瘤细胞中VEGF的表达,其中5μmol/L Cyclopamine组VEGF的表达分别下降至(33.3±3.3)％(U87细胞),(27.1±3.0)％(SHG44细胞);10 μmol/L组VEGF的表达分别下降至(14.7±29)％( U87),(16.3±2.4)％(SHG44).结论 部分胶质瘤中存在Hedgehog/Gli1信号通路活化,而且这一信号通路活化程度与胶质瘤的血管新生密切相关.     

RNA干扰抑制Cyr61表达对人脑胶质瘤细胞生物学行为的影响

目的 观察RNA干扰技术沉默Cyr61基因表达对人脑胶质瘤U251细胞生物学行为的影响.方法 针对Cyr61 mRNA的序列设计合成小干扰RNA(siRNA)的DNA模板,构建pRNAT-Cyr61重组质粒,转染人脑胶质瘤U251细胞;RT-PCR和Western blot检测其对U251细胞内源性Cyr61表达的影响;用噻唑蓝(MTT)比色法观察U251细胞体外增殖活性的变化;用Transwell 小室法检测U251细胞体外侵袭能力的改变;流式细胞仪检测U251细胞凋亡并用透射电镜观察凋亡后的细胞形态学变化.结果 pRNAT-Cyr61重组质粒在mRNA及蛋白水平分别显著抑制Cyi61基因表达,抑制率分别最高达到74.87%和78.23%;U251细胞的体外生长抑制率最高达68.15%,侵袭细胞数下降至(46.00±2.82)个;U251细胞凋亡率最高达53.16%.结论 pRNAT-Cyt61可抑制Cyr61在人脑胶质瘤U251细胞中的表达,并抑制细胞的增殖活性和侵袭能力,促进细胞凋亡.     

藤梨根对人脑胶质瘤U251细胞的影响及其机制

目的 探讨藤梨根对人脑胶质瘤U251细胞的作用及其机制.方法 常规培养人脑胶质瘤细胞株U251,分别加入不同浓度(50、100、200 mg/L)藤梨根作用48 h后细胞计数试剂盒(CCK-8)法检测U251的细胞活性;取50 mg/L藤梨根作用48 h后的细胞,反转录-聚合酶链反应(RT-PCR)法检测信号转导和转录活化因子3(STAT3) mRNA的表达,Western blot检测STAT3蛋白的表达.结果 藤梨根作用48 h后U251细胞凋亡率明显增加,不同浓度的凋亡率分别为50 mg/L:(26.51士1.30)％、100 mg/L:(55.92 ±2.40)％、200mg/L:(63.69±2.70)％;50 mg/L藤梨根处理后的U251细胞中STAT3 mRNA和蛋白表达水平均下调,检测其中相关蛋白表达结果显示,藤梨根处理组中磷酸化STAT3(p-STAT3)和B淋巴细胞瘤/白血病-2(bcl-2)的表达下调,而bcl-2相关X蛋白(bax)的表达上调.结论 藤梨根可以抑制脑胶质瘤细胞的增殖,其机制可能与藤梨根调控STAT3信号通路有关.     

LRIG3基因过表达对神经胶质瘤细胞株U251与U87增殖及增殖细胞核抗原和Ki-67表达的影响

目的 探讨过表达LRIG3基因对神经胶质瘤细胞株U251与U87增殖及增殖细胞核抗原(PCNA)和Ki-67表达的影响及其机制。方法 用携带LRIG3过表达特异性序列和只含空白载体的质粒用慢病毒法感染胶质瘤细胞株U251与U87,筛选稳定株,分别分成实验组和对照组,通过逆转录-聚合酶链反应(RT-PCR)和Western blot法检测各组细胞LRIG3表达的变化,应用噻唑蓝(MTT)比色法检测病毒感染后对胶质瘤细胞株U251与U87增殖的影响,用免疫组织化学链霉亲和素生物素复合物(SABC)法分别检测各组细胞中PCNA和Ki-67的表达差异。结果 LRIG3过表达组细胞中LRIG3 mRNA水平与对照组比较分别升高67.6％( U251)和79.9％ (U87),LRIG3蛋白表达水平分别升高62.3％(U87)和91.0％( U251)。MTT法结果显示两实验组细胞增殖率均低于相应对照组。U251细胞对照组PCNA阳性率为(47.81 ±4.67)％,实验组为(27.49±3.17)％,U87细胞对照组PCNA阳性率为(55.50±4.01)％,实验组为(33.60±4.82)％,差异均有统计学意义(P＜0.05)。U251细胞对照组中Ki-67的阳性率为(48.50±6.11)％,实验组为(24.30±3.76)％,U87细胞对照组Ki-67阳性率为(55.20±4.19)％,实验组为(23.50±4.60)％,差异均有统计学意义(P＜0.0l)。结论 LRIG3基因过表达可减少胶质瘤细胞的增殖。     

胶质瘤细胞放射敏感性与ATM蛋白表达的关系

目的 探讨胶质瘤细胞放射敏感性与ATM蛋白表达关系.方法 采用流式细胞仪检测22例原代培养胶质瘤细胞中ATM蛋白的表达,用噻唑蓝(MTT)比色法检测胶质瘤细胞以60C0 2 Gy放射剂世照射后的存活分数(SF2),探讨ATM蛋白的表达量与胶质瘤放射敏感性的相关性;同时检测其中5例胶质母细胞瘤细胞及U251细胞系经60Co照射前后ATM蛋白表达量,以了解放射对ATM蛋白表达的影响.结果 原代培养的胶质瘤细胞形态多样;SF2平均值为0.417±0.176(0.162.0.735).在胶质瘤Ⅳ级与Ⅱ、Ⅲ级间差异有统计学意义(P<0.05);ATM蛋白表达水平随胶质瘤恶性程度的增高而增加,在高、低级别间差异有统计学意义(P<0.05);直线相关与回归分析显示:ATM蛋白表达水平与SF2呈显著正相关(r=0.857,P<0.05);5例原代培养的胶质母细胞瘤细胞及U251细胞系经照射后ATM蛋白表达水平提高.结论 ATM蛋白的表达水平与胶质瘤放射敏感性密切相关,胶质瘤中存在不同放射敏感性的细胞群,放射治疗应体现个体化原则.     

N端α位乙酰基转移酶10在甲状腺癌中的表达及其对TPC-1甲状腺癌细胞中可溶性Fas受体表达的影响

目的探讨N端α位乙酰基转移酶10(Naa10)在甲状腺癌中的表达及对TPC-1甲状腺癌细胞中可溶性Fas受体(sFas)表达的影响。方法蛋白质印迹法(Western blot)及实时荧光定量-聚合酶链反应(Real-time PCR)检测甲状腺癌及癌旁组织中Naa10蛋白及mRNA表达, 将TPC-1细胞随机分为siRNA Naa10(siRNA组)和siRNA NC组(对照组), 培养48 h, Western blot及Real-time PCR检测Naa10蛋白及mRNA表达, MTT法检测细胞活力, 细胞克隆形成实验检测细胞克隆能力, Hoechst染色检测细胞凋亡, 酶联免疫吸附法(ELISA)及Real-time PCR法检测sFas、sFas配体(sFasL)蛋白及mRNA表达, Western blot法检测剪切的含半胱氨酸的天冬氨酸蛋白水解酶(cleaved Caspase)-3、cleaved Caspase-8、cleaved Caspase-9蛋白表达, 组间比较采用t检验。结果癌症组Naa10蛋白及mRNA表达量高于癌旁组(0.78±0.07比0.32±0.0...     

骨形成发生蛋白4在阿霉素诱导的U251胞抑制中的表达

目的 观察骨形成发生蛋白4(BMP4)和Smad4在阿霉素诱导U251细胞抑制中的表达变化.方法 应用噻唑蓝(MTT)检测空白组和阿霉素组U251细胞增长活性,应用公式(1-阿霉素组A/空白组A)×100%计算阿霉素组U251细胞增长抑制率.应用荧光定量聚合酶链反应(PCR)和Western blot检测空白组和阿霉素组BMP4和Smad4的表达.结果 阿霉素在24、36、48、60、72 h对细胞抑制率为分别为10%、21%、56%、49%、43%.在24 h抑制率为最高(P<0.05).荧光定量PCR显示阿霉素组与对照组比较,BMP4表达增加了(13.0±0.7)%(P<0.05),Smad4表达增加了(35.0±1.0)%(P<0.05),Western blot显示BMP4和Smad4表达分别增加了23%和38%(P<0.05).结论 阿霉素抑制U251细胞的生长可能通过提高BMP4和Smad4的表达来实现,BMP4可能成为胶质瘤治疗的新靶点.     

常春藤皂苷元对人胶质瘤细胞株U251MG凋亡及迁移侵袭的影响及其机制

目的探讨常春藤皂苷元(Hederagenin)对人胶质瘤(Glioma)细胞株U251MG凋亡的影响和机制。方法应用不同剂量的Hederagenin作用于人胶质瘤细胞株U251MG 48 h后应用噻唑蓝(MTT)法检测细胞活性。U251MG细胞分为实验组(给与80 μg/ml Hederagenin干预)及对照组[给与无血清的杜尔伯科改良伊格尔(DMEM)培养液], 流式细胞术检测细胞凋亡;划痕实验和Transwell小室实验检测细胞的迁移侵袭能力;蛋白质印迹法(Western blot)技术检测各组U251MG细胞凋亡及迁移侵袭相关蛋白的变化。多组数据间比较采用单因素方差分析, 两组数据比较采用t检验。结果 MTT结果显示, 实验组U251MG细胞活性明显低于对照组, 且随药物剂量增加效应更加明显(F=288.946, P<0.01)。流式细胞术(FCM)结果显示, Hederagenin作用于U251MG细胞48 h后实验组细胞凋亡率明显高于对照组[(21.07±4.85)%比(5.12±1.52)%, t=7.687, P<0.01], 实验组细胞的迁移率明显低于对照...     

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.     

卡氮芥联合全反式维甲酸诱导脑胶质瘤的凋亡及其分子机制

C6、U251细胞G1期比例分别由(42.18±2.52)%至(63.04±4.05)%、(57.14±2.52)%至(69.50±4.05)%,C6、U251细胞凋亡率2.46±1.02至17.43±2.03、10.36±1.76至21.32±2.03;Cyclin E、CDK2 mRNA表达下调,p27Kip1 mRNA表达上调.结论 BCNU与ATRA协同应用诱导脑胶质瘤细胞的凋亡,其诱导凋亡的分子机制可能是通过改变相关细胞周期蛋白导致细胞周期改变.     

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.