七氟醚后处理对大鼠心肌缺血再灌注时细胞凋亡的影响

目的 评价七氟醚后处理对大鼠心肌缺血再灌注时心肌细胞凋亡的影响.方法 健康雄性Wistar大鼠45只,体重250～ 280 g,采用随机数字表法,将大鼠随机分为3组(n=15):假手术组(S组)、心肌缺血再灌注组(I/R组)和七氟醚后处理组(Spo组).I/R组和Spo组采用结扎左冠状动脉前降支30 min时进行再灌注120 min的方法制备心肌缺血再灌注损伤模型,S组仅在左冠状动脉前降支下穿线.Spo组进行七氟醚后处理,于再灌注前1 min时吸八七氟醚,呼气末浓度2.5％,持续5min.于再灌注120 min时取左室心肌组织,测定缺血危险区和梗死区体积,计算缺血危险区和梗死区体积百分比.取左室缺血危险区心肌组织,测定心肌细胞凋亡指数,测定凋亡相关蛋白Bcl-2和Bax的蛋白及其mRNA的表达,计算Bcl-2/Bax比值.结果 与S组比较,I/R组心肌梗死区体积百分比和心肌细胞凋亡指数升高,Bcl-2、Bax蛋白及mRNA表达上调,Bcl-2/Bax比值降低(P＜0.05);与I/R组比较,Spo组心肌梗死区体积百分比和心肌细胞凋亡指数降低,Bax蛋白及mRNA表达下调,Bcl-2蛋白及mRNA表达上调,Bcl-2/Bax比值升高(P＜0.05).结论 七氟醚后处理通过上调Bcl-2表达,下调BBax表达,改善Bcl-2/Bax平衡,抑制心肌细胞凋亡,从而减轻大鼠心肌缺血再灌注损伤.     

舒芬太尼后处理对犬心肌缺血/再灌注Bcl-2、Bax的影响及其与JAK2-STAT3信号通路的关系

目的 研究舒芬太尼后处理对心肌缺血/再灌注损伤(ischemiia/reperfusion injury,I/RI)细胞凋亡的影响以及与信号通路JAK2-STAT3的关系.方法 健康杂种家犬24只,体重10 kg～15 kg,按随机数字表法分为4组(每组6只):假手术组(Sham组,只穿线,不结扎),心肌缺血/再灌注(ischemia/reperfusion,I/R)组,舒芬太尼后处理组(SPO组,于再灌注前5min静脉注射舒芬太尼0.6 μg/kg),舒芬太尼后处理+AG490组(SPO+AG490组,于再灌注前5 min静脉注射l mg/kg AG490,特异性的JAK2抑制剂),除Sham组外,所有犬心脏都经历30 min缺血和120 min再灌注.再灌注120 min时,取各组缺血区心肌组织,采用末端脱氧核苷酸转移酶介导的dUTP原位切口末端标记(terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling,TUNEL)法测定心肌细胞的凋亡情况,免疫组化法测定各组Bcl-2、Bax以及磷酸化STAT3 (p-ATAT3)蛋白的表达,并计算Bcl-2和Bax表达的比值(Bcl-2/Bax).结果 再灌注120 min时,可在I/R组缺血区心肌组织中检测到大量凋亡心肌细胞(63.9±4.0)％,而舒芬太尼后处理显著降低心肌细胞凋亡指数(30.7±1.5)％;与Sham组比较,I/R组、SPO组和SPO+AG490组Bcl-2与Bax表达上调,I/R组Bcl-2/Bax比值降低,SPO组Bcl-2/Bax比值升高;舒芬太尼后处理使p-STAT3表达明显增加,特异性的阻断剂AG490抑制了舒芬太尼后处理对心肌I/RI凋亡的作用,即抑制p-STAT3表达的增加. 结论 舒芬太尼后处理对心肌I/RI细胞凋亡有一定的抑制作用,通过激活JAK2-STAT3信号转导通路上调Bcl-2蛋白和下调Bax蛋白来发挥作用.     

依那普利后处理对肢体缺血再灌注诱发大鼠心肌损伤的影响

目的 评价依那普利后处理对肢体缺血再灌注诱发大鼠心肌损伤的影响.方法 健康雄性SD大鼠36只,体重200 ～ 250 g,采用随机数字表法,将其分为3组(n=12)∶假手术组(S组)、缺血再灌注组(I/R组)和依那普利后处理组(EP组).I/R组和EP组采用橡皮带环绕结扎大鼠双后肢根部3h,再灌注3h的方法制备肢体缺血再灌注模型.再灌注前30 min时,EP组经颈内静脉注射依那普利0.04 mg/kg,S组和I/R组经颈内静脉注射等容量生理盐水.再灌注3h时,处死大鼠,取心肌组织,采用TUNEL法检测心肌细胞凋亡,计算细胞凋亡指数;采用免疫组化法测定Bcl-2和Bax的蛋白表达;采用黄嘌呤氧化酶法测定SOD活性;采用硫代巴比妥法测定MDA含量.结果 与S组比较,I/R组和EP组心肌细胞凋亡指数和MDA含量升高,Bax蛋白表达上调,Bcl-2蛋白表达下调,SOD活性降低(P＜0.05);与I/R组比较,EP组心肌细胞凋亡指数和MDA含量降低,Bax蛋白表达下调,Bcl-2蛋白表达上调,SOD活性升高(P＜0.05),心肌病理学损伤减轻.结论 依那普利后处理可减轻肢体缺血再灌注诱发大鼠心肌损伤,其机制可能与减少心肌细胞凋亡和减轻脂质过氧化反应有关.     

七氟烷预处理对大鼠心肌缺血再灌注损伤时细胞凋亡的影响

目的 探讨七氟烷预处理对大鼠心肌缺血再灌注损伤时细胞凋亡的影响.方法 成年雄性SD大鼠64只,体重270～350 g,随机分为4组(n=16):假手术组(S组)仅穿线不结扎,心肌缺血再灌注组(I/R组)阻断左冠状动脉前降支缺血30 min,恢复灌注2 h制备心肌缺血再灌注损伤模型,七氟烷组(Sevo组)吸入2.5%七氟烷30 min,七氟烷预处理+心肌缺血再灌注组(SR组)吸入2.5%七氟烷30 min,15 min后制备模型.于再灌注2 h时随机取4只大鼠处死取左心室,采用氯化三苯四唑染色法测定心肌梗死范围,随机取4只大鼠处死取左心室,采用TUNEL法检测凋亡心肌细胞,计算凋亡指数,于缺血前即刻和再灌注2 h时分别随机取4只大鼠处死取左心室,采用Western blot法测定Bcl-2及caspase-3的蛋白表达水平.结果 与S组相比,再灌注2 h时I/R组和SR组心肌梗死范围增大,心肌细胞凋亡指数升高,caspase-3蛋白表达上调,Sevo组Bcl-2蛋白表达上调,I/R组Bcl-2蛋白表达下调,Sevo组和SR组缺血前即刻Bcl-2蛋白表达上凋(P＜0.05);与I/R组相比,再灌注2 h时SR组心肌梗死范围缩小、心肌细胞凋亡指数降低,Sevo组和SR组Bcl-2蛋白表达上调,SR组caspase-3蛋白表达下调(P＜0.05);与缺血前即刻相比,I/R组和SR组再灌注2 h时Bcl-2蛋白表达下调,caspase-3蛋白表达上调(P＜0.05).结论 七氟烷预处理可通过抑制细胞凋亡减轻大鼠心肌缺血再灌注损伤.     

舒芬太尼后处理对大鼠心肌缺血再灌注时细胞凋亡的影响

目的 探讨舒芬太尼后处理对大鼠缺血再灌注时心肌细胞凋亡的影响.方法 健康雄性SD大鼠36只,体重250 ～ 280 g,采用随机数字表法,将大鼠随机分为3组(n=12):假手术组(S组)、缺血再灌注组(I/R组)和舒芬太尼后处理组(SP组).采用结扎左冠状动脉30 min,再灌注120min的方法制备心肌缺血再灌注模型.S组只挂线不结扎左冠状动脉;SP组于再灌注即刻静脉注射舒芬太尼3.0 μg/kg.于缺血再灌注期间记录HR和MAP.于再灌注120 min时,处死大鼠,取心脏,测定心肌梗死面积,采用RT-PCR测定心肌Bax mRNA和Bcl-2 mRNA的表达,采用TUNEL法检测心肌凋亡细胞,计算凋亡指数.结果 三大鼠各时点HR比较差异无统计学意义(P＞0.05);与S组比较,I/R组心肌缺血再灌注期间MAP降低(P＜0.05),SP组差异无统计学意义(P＞0.05),I/R组和SP组凋亡指数和Bax mRNA表达水平升高,I/R组Bcl-2 mRNA表达水平降低,SP组Bcl-2 mRNA表达水平升高(P＜0.05);与I/R组比较,SP组心肌梗死面积、凋亡指数和Bax mRNA表达水平降低,Bcl-2 n.RNA表达水平升高(P＜0.05).结论 舒芬太尼后处理可能通过上调Bcl-2表达,下调Bax表达,抑制细胞凋亡,从而减轻大鼠心肌缺血再灌注损伤.     

氟比洛芬酯后处理对大鼠局灶性脑缺血再灌注时神经元凋亡的影响

目的 评价氟比洛芬酯后处理对大鼠局灶性脑缺血再灌注时神经元凋亡的影响.方法 健康雄性Wistar大鼠64只,体重260～310 g,采用随机数字表法,将其随机分为4组(n＝16):假手术组(S组)、缺血再灌注组(I/R组)、脂微球溶剂组(LM组)和氟比洛芬酯10 mg/kg组(FB组).I/R组、LM组和FB组采用改良线栓法制备大鼠局灶性脑缺血再灌注损伤模型,缺血2h,再灌注24 h;S组仅分离血管.再灌注即刻FB组尾静脉注射氟比洛芬酯10 mg/kg,LM组尾静脉注射脂微球溶剂1ml/kg,S组和I/R组尾静脉注射等容量生理盐水.再灌注24h时行神经功能缺陷评分,然后处死大鼠,取脑组织,计数缺血侧凋亡神经元,计算神经元凋亡指数;采用Western blot法检测Bcl-2和Bax蛋白的表达,计算Bcl-2/Bax比率.结果 与S组比较,I/R组、LM组和FB组神经功能缺陷评分和神经元凋亡指数升高,I/R组和IM组Bcl-2蛋白表达下调,Bax蛋白表达上调,Bcl-2/Bax比率降低(P<0.05);与I/R组土土比较,LM组各指标差异无统计学意义(P＞0.05),FB组神经功能缺陷评分和神经元凋亡指数降低,Bcl-2蛋白表达上调,Bax蛋白表达下调,Bcl-2/Bax比率升高(P<0.05).结论 氟比洛芬酯后处理通过调节Bcl-2与Bax的失衡,抑制神经元凋亡,减轻大鼠局灶性脑缺血再灌注损伤.     

依托咪酯后处理对大鼠脑缺血再灌注时细胞凋亡的影响

目的 评价依托咪酯后处理对大鼠脑缺血再灌注时细胞凋亡的影响.方法 清洁级健康雄性SD大鼠32只,体重250～300 g,采用随机数字表法,将大鼠随机分为4组(n=8):假手术组(S组)、缺血再灌注组(I/R组)、脂肪乳组(L组)和依托咪酯后处理组(Ep组).采用栓塞右侧大脑中动脉2h恢复灌注的方法制备大鼠脑缺血再灌注模型.Ep组于再灌注即刻腹腔注射依托咪酯乳剂20 mg/kg(1 ml/100 g),I/R组和L组分别给予等容积生理盐水和脂肪乳.于再灌注24h时处死大鼠,取缺血侧脑组织,HE染色后光镜下观察病理学结果,采用TUNEL法检测凋亡细胞,计算凋亡指数,采用免疫组化染色法测定Bcl-2和Bax的表达,计算Bcl-2与Bax表达的比值(Bcl-2/Bax).结果 与S组比较,I/R组、L组和Ep组细胞凋亡指数升高,Bcl-2和Bax表达上调,Bcl-2/Bax升高(P＜0.05);与I/R组和L组比较,Ep组细胞凋亡指数降低,Bcl-2表达上调,Bax表达下调,Bcl-2/Bax升高(P＜ 0.05);I/R组和L组上述指标差异无统计学意义(P＞0.05).Ep组脑组织病理学损伤较I/R组明显减轻.结论 依托咪酯后处理减轻大鼠脑缺血再灌注损伤的机制与调节Bcl-2和Bax的平衡表达,抑制细胞凋亡有关.     

异丙酚对大鼠小肠缺血再灌注时粘膜上皮细胞凋亡的影响

目的 探讨异丙酚对大鼠小肠缺血再灌注时粘膜上皮细胞凋亡的影响及其机制.方法 健康Wistar大鼠24只,随机分为3组(n=8):假手术组(S组)、缺血再灌注组(I/R组)和异丙酚+缺血再灌注组(P+I/R组).夹闭肠系膜上动脉,缺血1 h,再灌注2 h,制备小肠缺血再灌注损伤模型.S组和I/R组缺血前10 min开始经股静脉持续输注生理盐水10 ml·kg-1·h-1,P+I/R组静脉注射异丙酚10 mg/kg,以后持续输注异丙酚10 mg·kg-1·h-1.取空肠组织3 cm,常规制备全层石蜡切片,行HE染色,光镜下观察小肠组织病理学;免疫组化法检测Bcl-2、Bax蛋白的表达;TUNEL法检测小肠粘膜上皮细胞凋亡,计数凋亡细胞及总细胞,计算小肠粘膜上皮细胞凋亡指数.结果 与S组比较,I/R组和P+I/R组Bcl-2和Bax蛋白表达上调,Bcl-2/Bax增加,小肠组织损伤程度增强,小肠粘膜上皮细胞凋亡指数增高(P＜0.01或0.05);与I/R组比较,P+I/R组Bcl-2蛋白表达上调,Bax蛋白表达下调,小肠组织损伤程度减轻,小肠粘膜上皮细胞凋亡指数降低(P＜0.01).结论 异丙酚可减轻大鼠小肠缺血再灌注损伤时粘膜上皮细胞凋亡,其机制与上调Bcl-2基因的表达和下调Bax基因的表达有关.     

丙泊酚对2型糖尿病大鼠心肌缺血-再灌注损伤时凋亡蛋白Bax和Bcl-2的影响

目的观察丙泊酚对2型糖尿病大鼠心肌缺血-再灌注损伤时凋亡蛋白Bax和Bcl-2表达的影响。方法雄性Wistar大鼠48只,随机均分为心肌缺血-再灌注组(CI组)、心肌缺血-再灌注+丙泊酚组(CP组)、假手术组(CC组),以及糖尿病心肌缺血-再灌注组(DI组)、糖尿病心肌缺血-再灌注+丙泊酚组(DP组)、糖尿病假手术组(DC组)。采用高脂高糖饮食复合腹腔注射链脲佐菌素(STZ)方法制备2型糖尿病模型。DI组和CI组采用结扎左冠状动脉前降支30min再灌注2h的方法制备心肌缺血-再灌注模型。DP组、CP组在缺血前10min开始静脉泵注丙泊酚6mg·kg-1·h-1至再灌注2h结束,DI组、CI组给予等容量的生理盐水;DC组、CC组仅穿线不结扎。再灌注结束后,取病变部分心肌,光镜下观察缺血心肌形态学改变,免疫组化法测定心肌Bax和Bcl-2表达水平,并计算Bcl-2和Bax表达的比值。结果与CC组比较,CI组和CP组Bcl-2、Bax表达明显上调,CI组Bcl-2/Bax明显下降(P0.05)。与CI组比较,CP组Bax表达明显下调,Bcl-2表达明显上调,Bcl-2/Bax明显升高(P0.05),DI组Bcl-2、Bax表达明显上调(P0.05)。与DC组比较,DI组和DP组Bcl-2、Bax表达明显上调,DI组Bcl-2/Bax明显下降(P0.05)。与DI组比较,DP组Bax表达明显下调,Bcl-2表达明显上调,Bcl-2/Bax明显升高(P0.05)。结论丙泊酚可上调抗凋亡蛋白Bcl-2表达、下调凋亡前蛋白Bax的表达,并减轻正常大鼠和2型糖尿病大鼠心肌缺血-再灌注损伤。     

瑞芬太尼对肝硬化大鼠肝脏缺血再灌注损伤的影响

目的 探讨瑞芬太尼对肝硬化大鼠肝脏缺血再灌注损伤的影响.方法 成年健康雄性SD大鼠30只,体重260～300 g,采用随机数字表法,将其随机分为3组(n=10):肝硬化组(C组)、肝硬化+肝缺血再灌注组(I/R组)和瑞芬太尼组(R组).C组、I/R组和R组采用四因素综合法制备大鼠肝硬化模型,I/R组和R组在肝硬化模型制备成功后1周制备大鼠70％肝脏缺血再灌注模型,R组于缺血前10 min开始静脉输注瑞芬太尼1μg·kg-1·min-至再灌注结束.于再灌注4h时取静脉血样和肝组织,测定血清ALT和AST活性、肝细胞Bcl-2和Bax表达及肝细胞凋亡情况,计算细胞凋亡指数,光镜下观察肝组织病理学结果.结果 与C组比较,I/R组血清ALT和AST的活性升高,肝细胞Bcl-2表达下调,Bax表达上调,细胞凋亡指数升高(P＜0.05);与I/R组比较,R组血清ALT和AST的活性降低,肝细胞Bcl-2表达上调,Bax表达下调,细胞凋亡指数降低(P＜0.05).R组肝组织病理学损伤轻于I/R组.结论 瑞芬太尼可减轻肝硬化大鼠肝脏缺血再灌注损伤,其机制与平衡肝细胞Bcl-2与Bax表达而抑制肝细胞凋亡有关.     

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.     

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.