非接触式共培养体系对脐带间充质干细胞向类髓核细胞的诱导分化效应

目的探讨人脐带间充质干细胞向类髓核细胞的分化潜能,为椎间盘退变性疾病的生物学治疗探索新的细胞来源。方法取人正常足月产婴儿脐带及成人椎间盘,分离消化华通胶组织和髓核组织,收集培养脐带间充质干细胞及成人髓核细胞。利用带有插入层的Transwell 6孔培养板进行细胞非接触式共培养,细胞比例为1∶1,以脐带间充质干细胞单独培养作为对照组。共培养1周后,提取脐带间充质干细胞总RNA,利用Real-Time PCR检测其Ⅱ型胶原、蛋白多糖及SOX9基因的相对表达改变。结果成功分离提取脐带间充质干细胞;Real-Time PCR检测结果显示实验组脐带间充质干细胞Ⅱ型胶原、蛋白多糖和SOX9基因相对表达较对照组显著增加,差异有统计学意义（P〈0.01）。结论人脐带间充质干细胞能够被髓核细胞诱导分化为类髓核细胞,有可能为椎间盘退变性疾病的生物学治疗提供一种新的细胞来源。     

非接触式共培养下两种同源间充质干细胞对退变髓核细胞生物学影响的比较研究

【摘要】 目的：比较非接触式共培养条件下两种同源间充质干细胞对退变髓核细胞生物学功能的影响。方法：取同一腰椎间盘突出症患者骨髓间充质干细胞（BMSCs）、脂肪间充质干细胞（ADSCs）和退变髓核细胞（NPCs）,两种间充质干细胞分别与髓核细胞在Tanswell 6孔板中进行非接触式共培养,与ADSCs共培养的NPCs为A组,与BMSCs共培养的NPCs为B组,以单独培养的NPCs为对照组。共培养7d后,提取3组髓核细胞总RNA,进行反转录后,利用Real-Time PCR检测其Ⅱ型胶原、蛋白多糖和SOX-9基因的相对表达量。结果：非接触式共培养7d后,Ⅱ型胶原、蛋白多糖和SOX-9基因相对表达量对照组分别是1.03±0.28、1.21±0.40和0.94±0.34,A组分别是3.49±0.55、3.88±2.11和2.41±0.91,B组分别是7.60±1.89、6.26±2.96和4.55±1.88。与对照组相比,A、B组髓核细胞Ⅱ型胶原、蛋白多糖和SOX-9基因相对表达显著增加（P<0.05）;A、B两组间相比也有显著性差异（P<0.05）。结论：非接触式共培养条件下骨髓间充质干细胞和脂肪间充质干细胞对退变髓核细胞均有一定的激活效应;骨髓间充质干细胞对退变髓核细胞的激活效应更强,可能更加适合于椎间盘退行性疾病的生物学治疗。     

两种同源间充质干细胞在接触式共培养体系下对退变髓核细胞生物学影响的比较

【摘要】 目的：比较两种人间充质干细胞在接触式共培养体系下对退变髓核细胞生物学功能的影响。方法：取同一例腰椎间盘突出症患者的退变髓核组织、脂肪组织和骨髓组织,分别分离培养退变髓核细胞（NPCs）、脂肪间充质干细胞（ADSCs）和骨髓间充质干细胞（BMSCs）。取3种细胞传代至第3代的细胞进行接触式共培养。共培养前,利用PKH26对第3代退变NPCs进行染色标记,然后按1∶1的细胞比例,将NPCs分别与ADSCs和BMSCs在普通6孔板内进行接触式共培养。实验分为3组,A组为单独培养的NPCs,为对照组;B组为与ADSCs共培养的NPCs;C组为与BMSCs共培养的NPCs。共培养第7天时,利用MoFlo高速流式细胞分选仪将共培养的细胞进行分选,获取各组NPCs。然后提取各组NPCs的总RNA,进行反转录后,再利用Real-Time PCR技术检测各组NPCs的Ⅱ型胶原、蛋白多糖和SOX-9基因的相对表达量。将Ⅱ型胶原、蛋白多糖和SOX-9基因的相对表达量按分组进行组间t检验,P＜0.05为有统计学差异。结果：从退变髓核组织、骨髓组织和脂肪组织中,均成功分离培养出NPCs、BMSCs和ADSCs。待各细胞传至第3代时,成功利用PKH26对NPCs进行染色标记。按实验分组将各细胞进行接触式共培养后第7天,成功利用MoFlo高速流式细胞分选仪将共培养细胞进行分选,获取各组NPCs。经提取各组NPCs的总RNA,反转录并进行Real-time PCR后,获取各组NPCs的Ⅱ型胶原、蛋白多糖和SOX-9基因相对表达量,A组分别为1.03±0.04,1.05±0.07,1.04±0.17;B组分别为5.26±0.24,7.71±0.21,3.84±0.25;C组分别为9.33±0.39,11.07±0.34,5.64±0.26;B、C组NPCs的Ⅱ型胶原、蛋白多糖和SOX-9基因相对表达量与A组比较显著性增加（P<0.05）;C组与B组比较,各指标基因相对表达量显著性增加（P<0.05）。结论：在接触式共培养条件下,BMSCs和ADSCs对退变NPCs均具有营养激活效应;BMSCs对退变NPCs的激活效应比ADSCs更好,对于椎间盘退行性疾病的生物学治疗可能更具优势。     

脐带华通胶间充质干细胞移植对退变椎间盘影响的实验研究

目的:探讨人华通胶间充质干细胞(Wharton′s jelly-derived mesenchymal stem cells,WJMSCs)移植对犬退变椎间盘的影响。方法:从新生儿脐带中提取WJMSCs,取增殖良好的第3代细胞,用含有绿色荧光蛋白的腺相关病毒(r AAV2-EGFP)感染标记细胞。选择20只健康成年比格犬作为实验动物,使用穿刺抽吸髓核组织法建立椎间盘退变模型(L4/5、L5/6、L6/7)。4周后将犬各节段椎间盘进行分组:L3/4为对照组(A组);L4/5为退变组(B组);L5/6为注射组(C组),注射生理盐水;L6/7为移植组(D组),移植绿色荧光蛋白标记的WJMSCs细胞悬液。造模术前、术后4、8、12、24周行腰椎X线及MRI检查。24周后处死动物取材进行冰冻切片荧光、HE染色及番红O染色等组织学检测,提取髓核组织总RNA,反转录后行Real Time PCR检测,观察蛋白多糖、Ⅱ型胶原、SOX-9及Ⅰ型胶原基因表达变化。结果:分离培养的WJMSCs贴壁生长,呈梭形形态,r AAV2-EGFP病毒感染后第3天表达绿色荧光。影像学检查结果显示各组椎间盘高度指数及相对灰度指数在造模术前、术后第4周无统计学差异,术后8、12、24周,D组椎间盘相对高度指数及相对灰度指数较B、C组高(P0.05),比A组低(P0.05)。术后24周,D组髓核组织冰冻切片内能够检测到GFP阳性的WJMSC细胞,HE染色显示D组髓核组织退变比B组和C组轻,番红O染色结果显示D组染色较B组和C组深,基因表达检测结果显示D组Ⅱ型胶原、蛋白多糖及SOX-9基因表达比B、C组高(P0.05),但比A组低(P0.05)。结论:人WJMSCs移植入犬退变椎间盘内能够存活,促进椎间盘细胞外基质Ⅱ型胶原及蛋白多糖合成,维持椎间盘高度及髓核含水量,能够有效延缓椎间盘退变进展。     

非接触性共培养BMSCs和髓核细胞时间差异性的实验研究

目的探讨在非接触性共培养环境下,BMSCs定向分化为类髓核细胞在共培养时间上的差异性,寻找适合体内移植的最佳时间。方法取6只8周龄健康新西兰大白兔(体重1.5～2.0 kg)骨髓及椎间盘髓核,分离、培养BMSCs和髓核细胞并进行免疫细胞化学鉴定。取原代髓核细胞和第2代生长良好的BMSCs体外建立非接触性共培养模型。观察共培养后第1、3、5代BMSCs的形态学变化并绘制生长曲线;RT-PCR检测共培养5、10、15 d BMSCsⅡ型胶原和蛋白聚糖mRNA表达;Western blot检测共培养5、10、15、20、25、30 d BMSCsⅡ型胶原和蛋白聚糖蛋白的表达。结果 BMSCs相对特异性标记物CD44、CD90表达阳性,造血细胞表面标记物CD34、CD45表达阴性。髓核细胞Ⅱ型胶原、蛋白聚糖表达阳性。共培养后2周BMSCs形态发生明显变化,呈多角形、不规则形;共培养后3代内,BMSCs生长速度无明显差异,随着传代次数增加,细胞增殖明显减慢。RT-PCR检测示共培养后10、15 d BMSCs蛋白聚糖和Ⅱ型胶原mRNA表达明显高于5 d时(P<0.05),而10 d与15 d时差异无统计学意义(P>0.05)。Western blot检测示共培养后随时间延长细胞表达Ⅱ型胶原和蛋白聚糖蛋白逐渐增加,5、10、15 d间差异有统计学意义(P<0.05),15 d后各时间点间比较差异无统计学意义(P>0.05)。结论在非接触性共培养环境下,BMSCs在髓核细胞诱导下可向类髓核细胞分化,表达Ⅱ型胶原和蛋白聚糖,在共培养15 d时达到相对稳定,此时较适合进行体内移植。     

髓核细胞鉴定的研究进展

目前髓核细胞尚无特异性细胞标记,通常认为来源于髓核并表达Ⅱ型胶原、SOX-9和聚集糖胺聚糖的细胞即髓核细胞。仅以Ⅱ型胶原、SOX-9和聚集糖胺聚糖来在定义髓核细胞显然是不足的,因为上述细胞标记无法鉴别髓核细胞与软骨细胞。干细胞治疗椎间盘退行性疾病是目前的研究热点之一,精确鉴定髓核细胞在干细胞治疗椎间盘退变的背景下具有重要意义。     

成人退变性椎间盘髓核细胞体外培养及形态学观察

目的通过对成人退变椎间盘髓核细胞的体外培养和形态学观察,进一步研究细胞因素在椎间盘退变中的作用机制。方法取5例患椎间盘突出症并行椎间盘摘除手术的成人髓核,分离后在培养基中进行髓核细胞培养,细胞染色、逆转录聚合酶链式反应、免疫荧光检测细胞Ⅰ、Ⅱ型胶原的表达。结果椎间盘髓核细胞可在体外培养,30d后方可进行传代,最佳的培养条件为胎牛血清/培养基体积分数为10%～20%,pH值7.0。髓核细胞中出现Ⅰ型胶原,并具有较高的表达,Ⅱ型胶原表达微弱。结论成人退变髓核细胞体外培养时间较长,细胞增殖能力低下,特定培养条件的摸索是成功与否的关键。     

人软骨终板干细胞与退变髓核细胞体外非接触共培养的实验研究

目的:探究人软骨终板干细胞(cartilage endplate stem cells,CESCs)与退变髓核细胞(nucleus pulposus cells,NPCs)在Transwell非接触共培养条件下的相互作用。方法:对取自因腰椎退行性疾病行腰椎间盘切除椎弓根螺钉内固定患者的软骨终板、退变髓核进行CESCs及NPCs的分离培养及鉴定。通过琼脂糖悬浮培养法获得CESCs的克隆,扩增后行流式技术及免疫荧光对CESCs进行干细胞表面标记的检测,取第三代CESCs与第一代NPCs进行实验,建立三个细胞培养组:CESCs单独培养组、NPCs单独培养组、CESCs与NPCs共培养组(分别接种于Transwell底部和上层插槽中进行非接触共培养)。在培养之后的不同时间点(3、5、7d),采用实时荧光定量PCR(Real-time PCR,RT-PCR)检测各组细胞中蛋白聚糖(Agg)、SOX-9及Ⅱ型胶原蛋白(CollⅡ)m RNA的表达变化情况,共培养7d后,采用Western-blot检测各组细胞中蛋白聚糖、Ⅱ型胶原蛋白、Sox-9蛋白的表达变化。结果:经过分离培养及鉴定,筛选出的细胞为CESCs(流式细胞计数分析,CESCs细胞表面的CD73、CD90、CD105阳性率分别为97.5%、98.7%、98.7%);共培养后,RT-PCR显示单独培养的CESCs在各检测时间点几乎无Agg、CollⅡ、SOX-9基因表达;而共培养组的CESCs在第5天开始出现Agg、CollⅡ、SOX-9基因表达(其表达量分别为0.10、0.11、0.15),与单独培养CESCs相比有统计学意义(P0.05);共培养组NPCs的Agg、CollⅡ及SOX-9基因表达量(其表达量分别为1.32、1.25、0.92)高于单独培养NPCs的表达量(P0.05),且随着时间延长逐渐升高,共培养与单独培养相比,差异有统计学意义(P0.05)。共培养7d后,Westernblot结果与RT-PCR结果一致,共培养组CESCs的Agg、CollⅡ、SOX-9蛋白表达量高于单独培养组(P0.05)。结论:CESCs与NPCs共培养时的相互作用能促使CESCs表达髓核细胞特异性标记物Agg、CollⅡ和SOX-9;通过相互作用,CESCs可增强NPCs表达自身特异性相关分子。     

大鼠髓核细胞来源外泌体对骨髓间充质干细胞向髓核样细胞分化的作用研究

目的:探讨大鼠髓核细胞来源外泌体对大鼠骨髓间充质干细胞(BMSCs)向髓核样细胞分化的作用。方法:采用贴壁法体外分离培养SD大鼠尾椎椎间盘髓核细胞和BMSCs,流式细胞术和三系分化实验鉴定BM-SCs。差速离心法分离髓核细胞外泌体,透射电镜观察其形态并使用蛋白免疫印迹(Western blot)检测其蛋白标志物CD81、Tsg101。分别使用荧光探针CM-DIO和CM-DIL标记BMSCs和髓核细胞外泌体,将两者共培养24h后在荧光显微镜下观察BMSCs对髓核细胞外泌体摄取情况。将第三代BMSCs分为三组:外泌体组,加入髓核细胞外泌体(50μg/ml);共培养组,与髓核细胞非接触式共培养;对照组,未做任何处理。分别于7、14、21d时应用荧光定量PCR(qRT-PCR)检测外泌体组和对照组Ⅱ型胶原(COL2A1)、蛋白多糖(ACAN)、SOX9的m RNA表达量。14d时应用qRT-PCR检测3组的COL2A1、ACAN、SOX9的m RNA表达量。结果:提取的第三代大鼠髓核细胞呈多角形或不规则形状,第三代BMSCs呈形态均一的长梭形。BMSCs高表达CD29(99.77%)、CD44(93.97%)、CD90(99.67%),低表达CD34(0.82%)、CD45(0.68%)。BMSCs成骨、成脂、成软骨诱导后染色均为阳性。透射电镜观察外泌体为30～100nm类圆形双层膜结构,其表达CD81、Tsg101蛋白,不表达Calnexin蛋白。荧光显微镜下CM-DIL标记的外泌体可被CM-DIO标记的BMSCs摄取。诱导7、14、21d后,外泌体组的COL2A1、ACAN、SOX9 mRNA表达量均显著高于对照组(P0.05)。14d时共培养组COL2A1、ACAN、SOX9的m RNA表达量均显著高于对照组,低于外泌体组(P0.05)。结论:大鼠髓核细胞外泌体可在体外诱导BMSCs向髓核样细胞分化,且诱导效果优于与髓核细胞的非接触式共培养,可为椎间盘组织工程提供一种有效的髓核细胞来源。     

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.