血管内皮生长因子和促血管生成素及其受体Tie2在肝细胞癌发生发展中的作用

目的探讨血管内皮生长因子(VEGF)和促血管生成素(Angiopietin)及其受体Tie2在启动肝细胞癌(HCC)血管生成中的调控机制及在HCC发生发展中的作用。方法新鲜HCC标本及癌旁肝组织38例,用实时定量逆转录-聚合酶链反应(RT-PCR)的方法检测Ang-1、Ang-2、Tie2和VEGF在各组织标本中的表达,以CD34标记新生血管内皮并计数微血管密度(MVD),分析上述因子在HCC组织和非癌肝组织中的表达差异、相互作用及其与MVD、临床病理特征之间的关系。结果Ang-1、Tie2在HCC和非癌肝组织中的表达差异无统计学意义(0．194 7±0．086 2比0．232 6±0．109 8,1．601 6±0．900 7比1．340 0±0．703 7,P均>0．05),而VEGF和Ang-2在HCC组织的表达高于非癌肝组织(1．038 0±0．572 0比0.832 3±0．182 4,0．621 3±0.417 6比0．442 9±0．330 1,P均<0．05);VEGF、Ang-2、Ang-2／1都与MVD和临床病理特征相关(P<0．01),但与组织分化程度无关(P>0．05)。结论Ang-2／1的失衡表达及其与VEGF和Tie2的共同作用是启动肝组织血管生成并诱发HCC发生、发展的重要因素;这种因素在HCC中的持续作用进一步促进了肿瘤血管生成和恶性生物学行为。     

肝细胞肝癌中COX-2、VEGF表达与肿瘤血管生成及其临床病理意义

目的　研究环氧合酶- 2 (COX- 2 )、血管内皮生长因子(VEGF)蛋白表达水平和肿瘤血管形成在肝细胞肝癌(HCC)组织中的临床病理意义。方法　应用免疫组化方法检测4 4例肝细胞癌患者手术切除石蜡包埋标本的COX- 2、VEGF的蛋白表达,抗CD34单克隆抗体显示血管内皮细胞,根据CD34阳性的血管内皮细胞计数来测定肿瘤微血管密度(MVD)。结果　高分化HCC中COX- 2蛋白表达显著高于中分化和低分化HCC(P<0 .0 5 ) ;转移组COX- 2蛋白表达显著高于无转移组(P<0 .0 1)。转移组VEGF蛋白表达显著高于无转移组(P<0 .0 1) ;无包膜HCC中VEGF蛋白表达显著高于有包膜HCC(P<0 . 0 5 )。转移组MVD显著高于无转移组(P<0 .0 1)。COX- 2和VEGF及VEGF和MVD之间表达的强弱呈强正相关(分别r=0 .6 2 6 1,r=0 .6 0 97;均P<0 .0 0 1) ;COX- 2和MVD之间无相关性(r=1.30 4 ,P>0 .0 5 )。结论　COX- 2的过度表达可能与高分化HCC致癌有关;COX- 2及VEGF均与肝癌的转移相关;COX- 2表达与VEGF表达可能有协同效应,共同促进了肿瘤血管的生成,从而促进HCC的生长、浸润和转移。     

膀胱移行细胞癌中血管内皮细胞生长因子表达与微血管密度的关系

目的 :探讨膀胱移行细胞癌中血管内皮细胞生长因子 (VEGF)表达与微血管密度 (MVD)的关系。方法 :对 4 3例膀胱移行细胞癌 (TCC)组织及 8例正常膀胱组织的石蜡切片采用免疫组织化学方法检测其VEGF的表达 ,计数微血管数。结果 :正常膀胱组织的VEGF阳性表达率和MVD分别为 0和 1 0 .0± 4 .6。膀胱TCC中G1 +G2 、G3+G4、Ta 1 、T2 +T3+T4的VEGF阳性表达率及MVD分别为 5 9.1 %和 1 7.4± 4 .4、90 .5 %和 2 3 .5±5 .6、5 9.1 %和 1 7.6± 4 .9、90 .5 %和 2 3.3± 5 .5。VEGF表达阳性与阴性组的MVD分别为 2 2 .3± 5 .1和 1 4 .6±4 .2。结论 :VEGF阳性表达率及MVD与膀胱TCC的病理特征有相关性     

胆系恶性肿瘤VEGF，bFGF的表达与微血管计数的关系

目的　研究胆囊癌和胆管癌组织中微血管 (microvessel,MV)计数和血管内皮生长因子(vascularendothelialgrowthfactor,VEGF)、碱性成纤维细胞生长因子 (basicfibroblastgrowthfactor,bFGF)表达及其意义。方法　以ABC免疫组化法对 40例胆囊癌和 42例胆管癌组织常规石蜡包埋切片分别检测MV、VEGF和bFGF。结果　 40例胆囊癌MV定量为 (6 6± 2 7)个 /HP ,VEGF、bFGF阳性率分别5 0 % (2 0 / 40 )和 5 3% (2 1/ 40 ) ;42例胆管癌MV定量为 (75± 19)个 /HP ,VEGF、bFGF阳性率分别为 5 5 %(2 3/ 42 )和 5 7% (2 4/ 42 )。高分化和未转移胆囊癌MV定量及VEGF、bFGF阳性率明显低于低分化腺癌〔(5 0± 2 4)vs.(89± 2 6 ) ,P <0 0 1;39%vs.6 7% ,P >0 0 5 ;39%vs.76 % ,P <0 0 5〕和转移癌〔(4 8± 9)vs.(86± 30 ) ,P <0 0 1;32 %vs .72 % ,P <0 0 5 ;36 %vs.72 % ,P <0 0 5〕 ;高分化和未转移胆管癌MV定量及VEGF、bFGF阳性率明显低于未分化癌〔(6 6± 15 )vs .(86± 2 3) ,P <0 0 5 ;41%vs.86 % ,P <0 0 5 ;35 %vs .76 % ,P <0 0 5〕和转移癌〔(6 3± 17)vs.(90± 15 ) ,P <0 0 1;40 %vs.76 % ,P <0 0 5 ,44 %vs .76 % ,P <0 0 5〕。VEGF( )、或bFGF( )或VEGF( )bFGF( )的胆囊癌和胆管癌MV定量明显     

胰腺癌微血管密度及血管内皮生长因子表达

目的　探讨胰腺癌组织中微血管密度 (MVD)和血管内皮生长因子 (VEGF)表达及其与淋巴结转移的关系。方法　采用免疫组织化学法及形态半定量方法对 31例胰腺癌和 7例正常胰腺组织进行MVD记数和VEGF表达检测。结果　胰腺癌组织中MVD记数、VEGF表达率分别为 11.0 5± 4.6 2、83% ,明显高于癌旁组织 5 .40± 1.71、2 0 %和正常胰腺组 6 .19± 1.5 6、14% (P <0 .0 1) ;淋巴结转移组MVD记数 ,VEGF表达分别为 13.0 0± 4.45、2 .0 0± 0 .95 ,明显高于无转移组 9.46±4.15、1.0 5± 0 .17和正常胰腺组 6 .19± 1.5 6、0 .14± 0 .38(P <0 .0 1)。MVD与VEGF表达呈正相关 (r =0 .418,P >0 .0 5 )。结论　MVD、VEGF表达高低可作为判断胰腺癌淋巴结转移、预后的指标。     

血小板源性内皮细胞生长因子与膀胱移行细胞癌的相关性研究

目的　探讨血小板源性内皮细胞生长因子 (PD ECGF)与膀胱移行细胞癌 (BTCC)的相关性。　方法　采用免疫组化方法对BTCC组织中PD ECGF、血管内皮生长因子 (VEGF)表达及微血管密度 (MVD)进行观察 ,结合 5 2例患者 5年随访结果分析。　结果　 5 2例患者中有完整随访资料者 5 0例 ,术后 5年无瘤生存率 4 2 .9% (2 1/ 4 9) ,总生存率 78.0 % (39/ 5 0 )。PD ECGF在G1肿瘤中阳性表达率 17.6 % (3/ 17) ,G2 5 9.3% (16 / 2 7) ,G3 87.5 % (7/ 8) ,P <0 .0 1。PD ECGF阳性组无瘤生存期 (31.87± 2 3.75 )个月 ,阴性组 (4 2 .19± 2 3.84 )个月 ,P <0 .0 5 ;总生存期阳性组 (4 8.87± 19.88)个月 ,阴性组 (5 7.19± 8.97)个月 ,P <0 .0 5。MVD极高组总生存期 (4 3.5 0± 2 2 .74 )个月 ,远低于高、中、低 3组的平均 (5 6 .4 6± 10 .98)个月 ,P <0 .0 5。随肿瘤MVD增高 ,VEGF阳性表达率显著增高 ,PD ECGF表达无明显增高。　结论　PD ECGF及MVD与BTCC恶性程度有显著相关性。     

环氧合酶2对胰腺癌新生血管生成的调节作用及其机制

目的　探讨环氧合酶 2 (COX 2 )在胰腺癌新生血管生成中的调节作用及其作用机制。方法　应用免疫组织化学染色研究人胰腺癌组织COX 2、血管内皮细胞生长因子 (VEGF)表达 ;同时标记肿瘤新生血管内皮细胞vWF和血管壁Ⅳ型胶原 ,计算肿瘤组织微血管密度 (MVD)。建立裸鼠胰腺癌细胞株PC 3移植瘤 ,观察选择性COX 2抑制剂Celebrex对肿瘤组织MVD的影响 ,并应用免疫组织化学染色和逆转录聚合酶链式反应 (RT PCR)研究裸鼠移植瘤组织VEGF表达变化。结果　COX 2在人胰腺癌组织中表达阳性率为 87 5 % ,VEGF阳性率为 5 8 3%。COX 2强阳性组MVD平均值显著高于COX 2弱阳性 +阴性组 ,P <0 0 1。VEGF阳性组MVD平均值高于VEGF阴性组 ,但无统计学差异 ,P >0 0 5 ;Pearson相关性检验结果表明COX 2与vWF和Ⅳ胶原标记的MVD均有明显的相关性 (相关系数分别为 0 5 99和 0 6 ) ,P <0 0 5。在裸鼠移植瘤的体内实验中 ,与对照组MVD(6 3 89± 13 6 7)相比 ,Celebrex处理组MVD为 32 2 5± 12 99,两者差异显著 ,P <0 0 1。免疫组织化学染色和RT PCR结果表明Celebrex处理组肿瘤组织VEGF表达较对照组明显下调。结论　COX 2与胰腺癌新生血管生成密切相关 ,其高表达促进了胰腺癌新生血管生成 ;可能作用机制是上调促血管生成因子VEGF     

血管瘤中缺氧诱导因子-1α的表达和血管生成的研究

目的　探讨缺氧诱导因子- 1α(HIF-1α)在血管瘤中的表达以及其和血管内皮细胞生长因子 (VEGF)、新生微血管密度 (MVD)的关系。方法　采用免疫组化SP法检测 2 8例婴幼儿血管瘤中HIF 1α、VEGF的蛋白表达和MVD。结果　 2 8例血管瘤中HIF-1α、VEGF的蛋白表达阳性率分别是6 4 % ,71.4 %。其中增生期和消退期HIF 1α阳性率分别为 87.5 %、33.3% (P <0.0 1) ,VEGF阳性率分别为 93.7%、4 1.7% (P <0.0 1) ;MVD分别为 73 4± 14 6 3、30 2± 9 1(P <0.0 1)。HIF 1α蛋白表达与VEGF成正相关 (P <0.0 1) ,HIF 1α和VEGF与MVD都成正相关 (P <0.0 1)。结论　血管瘤增生期血管内皮细胞存在着特殊的缺氧微环境 ,并通过HIF-1α表达水平提高调节VEGF等血管生成相关因子表达水平升高 ,促进了新生微血管生成     

VEGF、HIF-1 alpha、EGF在肝细胞癌中的表达及其临床意义

目的研究肝细胞癌 (HCC)中血管内皮生长因子 (VEGF)、缺氧诱生因子 1alpha(HIF 1α)和表皮生长因子 (EGF)的表达情况及其临床意义。方法采用免疫组织化学SABC法检测 36例HCC组织及其癌旁肝组织和 6例正常肝组织中VEGF、HIF 1α和EGF的表达情况 ,研究这 3个因子与HCC临床病理学资料、新生血管生成以及预后的关系。结果 36例HCC中VEGF、HIF 1α和EGF表达的阳性率分别为 89% (32 / 36 ) ,6 7% (2 4 / 36 )和 75 % (2 7/ 36 ) ,均高于相应的癌旁肝组织和正常肝组织 (P <0 0 5 )。光学显微镜下有静脉浸润的HCC组织中VEGF和HIF 1α的表达率分别为 96 % (2 3/ 2 4 )和 88% (2 1 / 2 4 ) ,高于光学显微镜下无静脉浸润者 (75 %和 2 5 % ) ,差异有显著意义 (P <0 0 5 )。VEGF阴性组术后 1、2年生存率均为 1 0 0 % ,弱阳性组分别为 87%和 2 2 % ,强阳性组分别为 5 4 %和 0 ,三组存活率的差异具有显著意义 (P <0 0 5 )。EGF阴性组术后 1、2年存活率分别为 1 0 0 %和 6 0 % ,弱阳性组均为 70 % ,强阳性组分别为 2 7%和 0。三组之间存活率的差异亦具有显著意义 (P <0 0 5 )。结论HCC组织中VEGF、HIF 1α和EGF呈过量表达。HCC组织中VEGF、EGF和HIF 1α的表达与HCC中新生血管生成以及预后不良有密切关系     

肝癌组织中缺氧与血管内皮生长因子过度表达的关系

目的　研究肝细胞癌 (HCC)中血管内皮生长因子 (VEGF)过度表达与HCC组织中缺氧的关系。方法　通过免疫组织化学链霉亲合素 生物素 过氧化物酶复合体 (SABC)法检测 3 6例HCC组织及其相应癌旁肝组织和 6例正常肝组织中缺氧诱生因子 1α(HIF 1α)、VEGF和微血管密度(MVD)的表达 ,并对这些指标进行相关分析。离体实验中用缺氧诱导剂氯化钴刺激人肝癌细胞系HepG2 ,采用半定量逆转录 聚合酶链反应 (RT PCR)和免疫组织化学检测VEGF的表达情况。结果　 3 6例HCC组织中HIF 1α强阳性 3例 (8.3 % )、弱阳性 2 1例 (5 8.3 % )、阴性 12例 (3 3 .3 % ) ;VEGF强阳性 16例 (4 4 .4% )、弱阳性 16例 (4 4 .4% )、阴性 4例 (12 .2 % )。等级相关分析显示HCC中VEGF的表达与MVD的表达、HIF 1α的表达与VEGF的表达均具有正相关关系 (P <0 .0 1)。氯化钴可以以浓度和时间依赖性的方式诱导HepG2细胞中VEGF的转录。结论　HCC中存在的缺氧是HCC组织中VEGF过度表达的始动因素之一。     

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.