CD204阴性人脂肪来源细胞体外成软骨潜能的初步研究

目的比较CD204+和CD204-两种人脂肪来源细胞的干细胞特性和体外诱导成软骨的能力。方法分离培养人脂肪来源细胞并进行流式细胞分选,分别获得CD204+和CD204-两种细胞。将这两种细胞培养扩增至第2代,观察其形态学特点;成脂、成骨定向诱导分化,油红O染色、茜素红染色定性;同时将两种细胞进行pellet成软骨诱导分化,比较体外诱导成软骨的能力,并以HE、Safranin O和Ⅱ型胶原免疫组化染色等进行鉴定。结果经流式细胞分选,脂肪来源细胞中CD204表达阳性率约为10%。分选后的CD204+和CD204-细胞均呈成纤维细胞样贴壁生长,但CD204-细胞具有更强的增殖能力。成脂诱导10 d后,两组细胞油红O染色均可见胞浆内有大量红染脂滴,但CD204+细胞具有更强的成脂潜能。成骨诱导2周后,两组细胞茜素红染色均可见钙结节红染,而CD204-细胞具有更强的成骨潜能。同时,细胞pellet成软骨诱导4周后,大体观可见CD204-细胞组pellet形成白色透明样软骨成分,而CD204+细胞组pellet外观微黄。HE和Ⅱ型胶原免疫组化染色均显示CD204-组pellet可见成熟软骨陷窝形成,Safranin O染色显示CD204-组软骨特异性细胞外基质沉积;而CD204+细胞组pellet则呈纤维化改变。结论脂肪组织来源的CD204-细胞具有干细胞的生物学特点,且有良好的成软骨潜能,可以成为软骨组织工程良好的种子细胞来源。     

正常与退变髓核的髓核间充质干细胞代谢活性及干性基因表达的比较

【摘要】 目的：比较来源于正常与退变髓核的髓核间充质干细胞（NPMSCs）的细胞代谢活性及干性基因表达情况。方法：收集6例非退变患者髓核组织（正常组）与6例腰椎间盘突出症患者的退变髓核组织（退变组）,采用酶消化法分离细胞,应用标准间充质干细胞培养基（standard MSC culture medium）进行细胞培养并观察细胞形态。两组内各取1例分离得到的细胞进行流式细胞仪检测间充质干细胞表面蛋白分子标记CD90、CD105、CD73、CD45、CD34及人类白细胞抗原（HLA）-DR表达情况;并进行成骨、成脂及成软骨诱导分化,诱导28d后分别应用茜素红染色鉴定细胞成骨能力、油红O染色鉴定细胞成脂能力、甲苯胺蓝染色鉴定细胞成软骨分化能力,并按照国际干细胞治疗协会（ISCT）提出的间充质干细胞的判定标准,对分离得到的细胞进行综合评估鉴定。采用CCK-8检测两组P2代NPMSCs的代谢活力。提取两组每例P2代细胞总RNA,行RT-PCR检测P2代细胞“干性维持”相关基因Oct4及Nanog表达情况。结果：两组P0代细胞均贴壁生长,形态学方面两组并无明显差异。免疫表型鉴定显示正常组和退变组间充质干细胞表面分子标记CD90、CD105、CD73表达比例分别高达96％、98％、95%以上,两组均低表达造血细胞标志物CD45、CD34、HLA-DR（均低于4%）。茜素红染色、油红O染色及甲苯胺蓝染色分别证实正常组与退变组细胞均可向骨、脂肪及软骨细胞三系诱导分化。上述结果证实分离得到的细胞即NPMSCs。细胞代谢活性测定示P2代细胞在培养后5d、7d、9d、11d、13d正常组细胞活性均强于退变组,两组细胞活性有统计学差异（P<0.05）。正常组“干性维持”相关基因Oct4及Nanog表达量分别为退变组的4.63±1.17、7.36±1.19倍,正常组均明显高于退变组（P<0.05）。结论：正常与退变髓核组织内均存在NPMSCs,但正常椎间盘来源的NPMSCs具有较强的细胞代谢活性,较”强的“干性维持”基因表达。     

脐血间充质干细胞的分离培养鉴定及诱导分化研究

目的：分离培养人脐血间充质干细胞（human umbilical cord blood-derived mesenchymal stem cells,hUCB-MSC）,体外观察其生长特性,并在特定条件下诱导分化,探讨其成脂成骨分化能力.方法：采用沉降法和密度梯度离心结合贴壁培养法自脐血中分离间充质干细胞,倒置显微镜下观察其形态及生长情况;流式细胞仪分析细胞周期并检测细胞表面标志物;用茜素红染色和油红0染色分别鉴定其成骨成脂分化能力.结果：纯化的hUCB-MSC贴壁生长,呈均一梭形,具有较强的增值能力,流式细胞仪分析P3代hUCB-MSC稳定表达间充质干细胞表面抗原标志CD73,CD105和CD90等,不表达造血标志CD34和CD45;成骨诱导后3周后细胞茜素红染色阳性;成脂诱导3周后细胞油红0染色阳性.结论：本实验分离的hUCB-MSC具有较强的增殖能力,表达间充质干细胞的表面标记,具有成骨成脂分化潜能.     

人骨膜细胞生物学特性的实验研究

目的 探讨人骨膜细胞体外培养的生物学特性. 方法 以胫骨骨膜组织为材料,采用组织块法分离细胞,完全培养基培养,通过倒置显微镜观察细胞形态学,锥虫蓝染色计数法检侧细胞增殖能力;流式细胞学分析细胞表面抗原.随机分为3组,成骨实验组和成软骨实验组分别加入不同的定向培养剂,对照组加入完全培养基,采用碱性磷酸酶染色、Von Kossa染色、甲苯胺蓝染色、Ⅱ型胶原免疫组化染色检测各组细胞的成骨和成软骨分化指标. 结果 骨膜细胞在体外培养条件下呈贴壁生长,细胞生长曲线证实骨膜细胞传至第9代仍保持良好的增殖能力,流式细胞仪检测证实细胞表面抗原CD90及CD105呈阳性;组织化学染色检测证实成骨实验组分化后细胞碱性磷酸酶及钙结节呈阳性,成软骨实验组分化后细胞蛋白聚糖及Ⅱ型胶原呈阳性,对照组各项指标均生阴性.结论 骨膜细胞体外培养细胞增殖能力强,具有间充质干细胞的特性和良好的成骨和成软骨分化潜能,其定向诱导分化的成骨细胞和软骨细胞均具有各自明显的细胞功能表达.     

诱导人孤雌胚胎干细胞向类间充质干细胞分化的实验研究

目的探索人孤雌胚胎干细胞在体外向类间充质干细胞诱导分化的方法 ,并鉴定所得细胞的生物学特性。方法人孤雌胚胎干细胞在无血清条件下悬浮培养,形成拟胚体,10d后在含血清条件下使拟胚体贴壁生长,7d后胰酶消化,所得细胞在含血清的培养液中传代、扩增。观察传代、扩增后细胞的形态学变化;用免疫荧光染色和流式细胞技术进行细胞表型分析;取第9代细胞进行成脂、成骨和成软骨诱导,9～28d后行特殊染色及RT-PCR分析。结果人孤雌胚胎干细胞在诱导分化后,形态与骨髓间充质干细胞相似,多次扩增传代后仍保持细胞形态和扩增能力。免疫荧光染色发现,细胞表达中胚层标志波形蛋白(Vimentin)。流式细胞分析显示,细胞表达CD29、CD105、CD166、CD44等间充质干细胞表面标志。特殊染色及RT-PCR分析显示:成骨诱导后,细胞碱性磷酸酶和茜素红染色阳性,碱性磷酸酶和Cbfa-1表达增加;成软骨诱导后,细胞Ⅱ型胶原染色阳性,Ⅱ型胶原和软骨寡聚基质蛋白(COMP)表达增强;成脂诱导后,细胞油红染色阴性,脂蛋白酶和Leptin无表达。结论人孤雌胚胎干细胞可以诱导、分化为间充质干细胞,并具有成骨、成软骨分化潜能。     

接种密度对大鼠髓核间充质干细胞的影响

[目的]比较不同细胞接种密度传代培养大鼠髓核间充质干细胞(nucleus pulposus-derived mesenchymal stem cells,NPMSCs)对NPMSCs的形态及表面标志物的影响。[方法]取12周龄SD大鼠椎间盘髓核组织体外消化获得原代细胞,待达到60%~70%融合时消化,并按接种密度分为三组,分别为低密度组(5个细胞/cm~2)、中密度组(100个细胞/cm~2)、正常密度组(10 000个细胞/cm~2)。培养至达到传代条件后,各组细胞均按10 000个细胞/cm~2在体外进行传代接种,进行形态学观察并检测干细胞的特征性表面标志(CD29、CD34、CD44、CD45、CD90)的表达情况。[结果]在细胞形态学方面,各接种密度组细胞均可呈旋涡状贴壁生长,但低密度组以集落样生长,细胞多呈长梭形,形态一致;中密度组和高密度组细胞中类圆形、多边形细胞增多,大量细胞出现形态不规则、细胞宽大扁平、折光性差。在细胞表面标志物方面,低密度组CD44、CD90的表达率明显高于中密度组和高密度组(P<0.05),而CD29、CD34、CD45差异无统计学意义(P>0.05)。[结论]低密度接种法可提高大鼠NPMSCs CD44及CD90的阳性率,纯化NPMSCs。     

CD105+滑膜间充质干细胞成软骨能力

目的 分选CD105+滑膜间充质干细胞(SMSCs),观察其增殖和向软骨细胞分化的能力.方法 酶消化滑膜组织分离SMSCs,流式细胞仪分选CD105+ SMSCs;第3、7天采用WST-1测定SMSCs的增殖能力;软骨诱导21 d进行免疫组织化学染色,检测蛋白聚糖和Ⅱ型胶原.结果 酶消化获取的SMSCs为星形或梭形,分选后SMSCs形态无明显变化.免疫荧光显示分选组CD105+细胞较未分选组明显增多.WST-1增殖检测提示两组细胞吸光度值3 d(0.376±0.012、0.329±0.012)、7 d(0.581±0.009、0.524±0.007)比较差异有统计学意义(P＜0.05).成软骨诱导培养21 d后,分选组甲苯胺蓝和Ⅱ型胶原染色均较未分选组多且深,说明CD105+ SMSCs合成更多软骨细胞外基质.结论 CD105+ SMSCs具有较强的增殖和成软骨能力,CD105+ SMSCs可成为软骨组织工程良好的种子细胞.     

酸环境对人髓核间充质干细胞生物学活性的影响

目的:观察酸环境对体外培养的成人髓核间充质干细胞(NPMSCs)生物学特征的影响,探讨椎间盘退变的可能机制。方法:用胶原酶消化法从6例脊柱侧凸矫形患者手术摘除的6个腰椎间盘(Pfirrmann椎间盘退变分级为Ⅰ级或Ⅱ级)髓核组织中分离细胞,体外培养,传代并观察细胞形态。取P2代细胞,利用流式细胞仪对分离得到的细胞表型CD34、CD45、CD73、CD90、CD105和人类白细胞抗原(HLA)-DR表达情况进行检测;用成骨、成软骨、成脂培养液诱导培养细胞,2周后分别用茜素红、甲苯胺蓝、油红O对细胞进行染色,观察其成脂、成骨、成软骨能力。按照国际干细胞治疗协会(ISCT)有关间充质干细胞(MSCs)的判定标准,对分离得到的细胞进行综合评估鉴定。在37℃、21%O2、5%CO2的细胞培养箱中用不同p H值(6.2、6.5、6.8、7.1、7.4)的DMEM10%血清培养液培养P2代细胞,1、3、5、7、9、11、13d后利用细胞增殖试剂盒(cell counting kit-8,CCK-8)检测细胞增殖活力(OD值),培养3d时借助流式细胞仪检测细胞凋亡率,不同p H值培养基培养28d时采用实时荧光定量(RT-PCR)检测P2代细胞"干性维持"基因Oct4、Nanog、Jag1、Notch1及酸离子通道家族蛋白基因ASIC1、ASIC2、ASIC3、ASIC4的m RNA表达情况。结果:P0代细胞均贴壁生长。P2代细胞免疫表型鉴定显示MSCs表面分子标记CD90、CD105、CD73表达比例分别高达96%、95%、94%以上,低表达CD45、CD34、HLA-DR(均低于4%)。茜素红染色、油红O染色及甲苯胺蓝染色分别证实分离的细胞均可向骨、脂肪及软骨细胞三系诱导分化。按照ISCT有关MSCs的判定标准,分离得到的细胞即NPMSCs。细胞代谢活性测定示P2代细胞在培养后1、3d各组间细胞OD值差异无统计学意义(P0.05);5d、7d、9d、11d、13d各组间细胞OD值差异有统计学意义(P0.05),且p H值越低细胞的OD值越小。p H值7.4组的细胞凋亡率均小于其余各组,各组间有统计学差异(P0.05)。p H值7.4组"干性维持"基因Oct4、Nanog、Jag1、Notch1及酸离子通道家族蛋白基因ASIC1、ASIC2、ASIC3、ASIC4的m RNA均明显高于p H值7.1、6.8、6.5、6.2组(P0.05)。随着培养液p H值降低,细胞的凋亡率升高,细胞干性维持基因及酸通道家族蛋白基因的m RNA表达降低。结论:低p H值的酸环境培养1、3d对成人NPMSCs增殖无明显影响,培养5d后明显抑制NPMSCs的增殖和基因表达,促进细胞凋亡,且随着p H降低作用越明显。     

不同来源椎间盘髓核间质干细胞特性及其多向分化能力研究

 目的 比较来源于先天性脊柱侧凸与腰椎间盘退变髓核组织中髓核间质干细胞增殖特性及其多向分化能力差别。方法 收集2 例先天性脊柱侧凸与2 例腰椎间盘突出患者的椎间盘组织, 采用酶消化法分离细胞, 在含体积分数为10%胎牛血清的低糖DMEM 完全培养液中培养髓核间质干细胞, 用MTT法及台盼蓝染色检测脊柱侧凸与椎间盘退变来源的两组细胞的代谢活力与增殖能力。流式细胞仪鉴定两组髓核间质干细胞CD44、CD105、CD29、CD24 表达差异, 观察两组细胞成骨、成脂、成软骨分化能力。结果 侧凸组髓核间质干细胞以梭形为主, 退变组髓核间质干细胞以多边形及三角形为主, 传代后两组细胞大多以纺锤梭形为主。MTT及台盼蓝染色法提示侧凸组代谢活力及增殖能力强于退变组。侧凸组和退变组髓核间质干细胞CD44、CD105、CD29 表达比例分别为97%~100%和88.7%~97%, CD24 表达均为阴性, 两者均不表达造血细胞标志物CD45、CD34、CD14、HLA-DR。侧凸组与退变组髓核间质干细胞均可向成骨、成软骨分化, 但均未向成脂分化。结论 先天性脊柱侧凸与椎间盘退变髓 核组织中均存在髓核间质干细胞, 前者的髓核间质干细胞具有较强的细胞代谢活性及增殖能力, 两者成骨、成软骨分化能力无差别, 但均无成脂能力。     

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.     

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.