头部重点低温脑复苏的细胞形态学实验研究—用计算机图象分析技术评判神经元受损程度

在以往系列实验研究初步阐明头部重点低温具有多方面有利于脑复苏的生化机理的基础上，本文试图从细胞形态学方面予以佐证。应用新西兰白兔３２只，４只为正常对照（Ⅰ组），其余均用改良“四血管法”造成脑缺血（３０ｍｉｎ）模型，分为缺血对照（Ⅱ组）、常温再灌注（Ⅲ组）和头部重点低温（２８±０．５℃）再灌注（Ⅳ组）三组，Ⅲ、Ⅳ组再分为再灌注３０、１８０和３６０ｍｉｎ三亚组，每组各４只。处死后在体灌注固定液固定脑组织，将全脑作冠状切片制成常规石腊切片。采用计算机图像分析技术，将脑组织１２个部位的神经元按预定标准判为Ａ（正常）、Ｂ（轻伤）、Ｃ（重伤）和Ｄ（坏死）四类，予以分别计数和算出所占百分比。结果：Ⅱ组与Ⅰ组相比，Ａ类神经元所占百分比明显减少，Ｂ、Ｃ、Ｄ类明显增多；Ⅲ组Ａ、Ｂ类神经元进一步减少，而Ｃ、Ｄ类更显著增多；Ⅳ组Ａ、Ｂ类神经元所占百分比显著高于Ⅲ组，Ｄ类则明显减少，随着时间从３０～３６０ｍｉｎ，Ｃ、Ｄ类所占百分比基本恒定。结论：头部重点低温（脑温２８℃上下）对缺血后再灌注损伤具有明显的抑制作用，正常神经元得以免于受损。随着低温时间适当延长，轻伤神经元可能获救，而重伤和坏死神经元则无复苏可能。     

Y27632对脊髓损伤微环境下新生大鼠背根节神经元轴突再生的影响

目的:探讨Rho蛋白激酶Ⅱ(Rho-associated coiled-coil-containing protein kinase Ⅱ,ROCK Ⅱ)特异性抑制剂Y-27632对脊髓损伤微环境下新生大鼠背根节(dorsal root ganglion,DRG)神经元轴突冉生和延长的影响.方法:取新生(<5d)SD大鼠胸腰段DRG神经元进行原代培养、提纯和鉴定.将健康雌性SD成年大鼠15只随机分为脊髓损伤组、假手术组和正常组,每组5只;用WD法制成T9平面脊髓损伤动物模型,造模7d后取T8～T10节段脊髓制作脊髓提取液.将新生大鼠DRG神经元分为5组进行培养:A组,DRG神经元+PBS;B组,DRG神经元+正常组脊髓提取液;C组,DRG神经元+假手术组脊髓提取液;D组,DRG神经元+损伤脊髓提取液;E组,DRG神经元+损伤脊髓提取液+不同浓度(5、10、20、30、40、50μmol/L)Y27632.培养2d后观察并比较各组新生大鼠DRG神经元轴突平均长度和微管(Tubulin βⅢ)荧光表达强度.结果:A、B和C组平均神经轴突长度及轴突远端tubulin βⅢ表达强度比较无统计学差异(P>0.05);D组明显减小,与A、B和C组分别比较有统计学差异(P<0.05).5、10μmol/L Y27632治疗组平均轴突长度以及轴突远端和生长锥tubulin μⅢ表达强度比D组有所增加(P<0.05),10μmol/L Y27632治疗组增加更明显,但小于A、B和C组(P<0.05).20～50μmol/L Y27632治疗组平均轴突长度以及轴突远端和生长锥tubulin βⅢ表达强度三组间比较无统计学差异(P>0.05);与5～10μmol/L Y27632治疗组、D组比较明显增加(P<0.05);与A、B、C组比较平均轴突长度无统计学差异(P>0.05),平均荧光密度明显增加(P<0.05).结论:损伤脊髓提取液能明显抑制新生大鼠DRG神经元轴突生长,导致轴突回缩.加入5～10μmol/L Y27632能促进轴突生长,20～50μmol/L Y27632更能明显促进轴突生长.     

冷脑保护液对大脑皮层组织丙二醛、血栓素A2及前列环素的影响

目的　研究深低温停循环间断灌注充氧脑保护液对大脑皮层组织丙二醛 (MDA)、血栓素 A2 (TXA2 )及前列环素 (PGI2 )的影响。　方法　杂种犬 10条 ,随机均分为两组。 A组 :单纯深低温停循环 12 0分钟 ;B组 :深低温停循环后间断灌注充氧脑保护液。两组动物分别于不同时相测定大脑皮层组织 MDA,TXA2 的代谢产物血栓素 B2(TXB2 )及 PGI2 代谢产物 6 - Keto- PGF1a的含量。　结果　恢复循环 45分钟后 ,A组 MDA和 TXB2 含量明显高于心肺转流术前 (P<0 .0 1) ,6 - Keto- PGF1a含量明显低于 B组 (P<0 .0 1)。　结论　深低温停循环间断灌注充氧脑保护液能明显减少恢复循环后大脑皮层组织 MDA和 TXA2 的生成 ,增加 PGI2 的生成 ,发挥其对大脑皮层组织的保护作用。     

TDZD-8对新生大鼠背根节神经元轴突再生影响的体外实验研究

目的:探讨葡萄糖原合成酶-3β(glycogen synthase kinase 3B,GSK-3β)的抑制剂TDZD-8对新生大鼠背根节(dorsal root ganglion,DRG)神经元轴突生长和延长的影响.方法:取新生(<5d)SD大鼠胸腰段背根节进行原代培养、提纯和鉴定.用WD法制成健康成年雌性SD大鼠T9平面完全性截瘫的脊髓损伤动物模型.造模7d后取T8～T10节段脊髓制作脊髓提取液.将不同浓度TDZD-8与成年大鼠脊髓提取液和新生大鼠DRG神经元分组培养:A组,DRG神经元+磷酸缓冲液(phosphate-bufered saline,PBS);B组,DRG神经元+正常脊髓提取液;C组,DRG神经元+假手术脊髓提取液:D组,DRG神经元+全瘫脊髓提取液;E组,DRG神经元+全瘫脊髓提取液+不同浓度TDZD-8.培养2d后观察并比较各组新生大鼠DRG神经元轴突平均长度和微管(Tubulin 8Ⅲ)荧光表达强度.结果:A组、B组和C组之间平均神经轴突长度及轴突远端Tubulin βⅢ表达强度比较,无统计学意义,D组明显减小,与A、B和C组分别比较,有统计学意义(P<0.01).0.5～3μM TDZD-8处理组平均轴突长度及Tubulin βⅢ荧光表达强度均明显高于A、B、C组,与D组比较,更为显著,差异均具有统计学意义(P<0.01).5～25μM TDZD-8处理组平均轴突长度与A、B、C组分别比较,明显缩短且有统计学意义(P<0.01),与D组比较无统计学差异(P>0.05);轴突远端Tuburn βⅢ表达比A、B、C、D组及0.5～3μM TDZD-8处理组明显增强,有统计学意义(P<0.01).结论:完全瘫痪脊髓提取液明显抑制DRG神经元轴突生长,轴突回缩.低浓度TDZD-8能促进轴突生长.形成多个轴突或轴突分支,而高浓度TDZD-8明显抑制轴突生长,导致轴突回缩.     

深低温停循环时不同脑保护方法对海马区神经元凋亡的影响

目的 通过观察海马区神经元的损伤情况，探讨深低温停循环(DHCA)时中枢神经系统损伤的机制及其保护方法。方法 北京农业大学实验用小型猪16头，体重22～25kg。鼻咽温降至18℃时分别给予如下处理90min：DHCA(I组)，顺行脑灌注(ACP，Ⅱ组)，逆行脑灌注(RCP，Ⅲ组)，RCP 尼莫地平(Ⅳ组)。复温120min至鼻咽温36℃。取左侧海马头部制备细胞悬液，AnnexinV—FITC染色，应用流式细胞仪分析细胞凋亡情况。电镜观察细胞超微结构的变化。结果 正常细胞百分比I组明显低于其他3组，Ⅱ组明显高于Ⅲ组，Ⅱ组、Ⅲ组与IV组之间差异无显著性；早期凋亡细胞百分比I组明显高于其他3组，Ⅱ组明显低于Ⅲ组，Ⅱ组、Ⅲ组与Ⅳ组之间差异无显著性；坏死细胞百分比I组明显高于其他3组，而其他3组之间差异无显著性；死亡细胞百分比I组明显高于其他3组，而其他3组之间差异无显著性(显著性界值P=0．05)。结论 DHCA后神经元发生凋亡、坏死和死亡，是术后神经功能障碍的主要原因；ACP使细胞凋亡和死亡减少，神经元保护作用最佳；RCP亦能使细胞凋亡和死亡减少，但神经元保护作用次于ACP；尼莫地平部分抑制了Ca^2 内流，脑保护效果一般。     

激光多普勒血流仪测量股骨头坏死的血流改变

目的 应用激光多普勒血流仪(laser doppler flowmetry,LDF)检测临床确诊为股骨头坏死患者的坏死区和头颈交界正常区的血液灌注量.方法 2007年至2008年对50例股骨头坏死患者82侧行股骨头钻孔减压自体干细胞植入,按照ARCO分期Ⅱ期为A组,46髋(ⅡA 6髋、ⅡB 22髋、ⅡC 18髋);Ⅲ期为B组,36髋(ⅢA 20髋、ⅢB 10髋、ⅢC 6髋),术中用激光多普勒血流仪检测股骨头坏死区及头颈交接区的血流灌注情况,对数据进行统计学处理.结果 A组坏死区灌注量为(30.2±3.0)PU,头颈交界区灌注量为(103.4±4.4)PU,B组坏死区灌注量为(30.6±2.8)PU,头颈交界区灌注量为(103.4±3.9)PU,A组和B组坏死区灌注量均低于正常区,二者比较差异具有统计学意义(P<0.01).而A组和B组之间坏死区和头颈交界区的灌注量差别无统计学意义(P>0.01).结论 LDF可以有效地检测股骨头坏死区血流灌注量减少,为进一步研究股骨头坏死的发病机制提供了理论依据,在股骨头坏死的研究中有应用价值.     

腺苷A1受体系统对兔脑缺血损伤的保护效应

目的　探讨腺苷A1 受体系统对兔脑缺血的保护作用。方法　家兔 2 4只随机分为对照组 (Ⅰ组 ,n =8)、缺血组 (Ⅱ组 ,n =8)和腺苷A1 受体激动药 +缺血组 (Ⅲ组 ,n =8) ,股动脉抽血至平均动脉压 35～ 40mmHg时 ,阻断双侧颈总动脉诱导脑缺血。观察术后第 3天海马CA1 区神经元密度。结果　 (1 )Ⅱ组神经元密度为 (76 50± 1 5 2 6)个 /毫米 ,显著低于Ⅰ组神经元密度 (2 0 8 1 3±1 1 0 8)个 /毫米 (P <0 0 5) ;而Ⅲ组神经元密度 [(1 30 78± 1 8 0 7)个 /毫米 ]明显高于Ⅱ组 (P <0 0 5)。结论　激活腺苷A1 受体系统能减轻脑缺血性损害     

右美托咪定对肝炎肝硬化患者围术期应激反应和免疫功能的影响

目的观察右美托咪定对肝炎肝硬化患者围术期应激反应和免疫功能的影响。方法择期行肝癌切除术的肝炎肝硬化患者40例,肝功能分级(Child-Pugh)为A或B级,ASAⅡ或Ⅲ级,采用数字表法随机均分为右美托咪定组(D组)和对照组(C组)。D组麻醉诱导前10min静脉泵注右美托咪定0.5μg/kg,随后以0.4μg·kg-1·h-1持续泵注至关腹;C组静脉泵注等量生理盐水。分别于麻醉诱导前30min(T0)、术毕即刻(T1)、术后24h(T2)、48h(T3)抽取外周静脉血,采用流式细胞仪测定T淋巴细胞亚群(CD3+、CD4+、CD8+、CD4+/CD8+)数量、NK细胞的百分比;并采用酶联免疫分析法检测T0~T3时血清炎性因子(IL-2、IL-10)浓度及T0、T2、T3时血清皮质醇(Cor)、醛固酮(ALD)、促肾上腺皮质激素(ACTH)含量。记录T0、插管即刻(Ta)、T1、拔管即刻(Tb)时SBP、DBP及CVP。结果 T1、T2时两组CD3+、CD4+、CD8+、CD4+/CD8+明显低于T0时,且C组明显低于D组(P0.05)。T1时两组NK细胞明显高于T0时,D组明显高于C组(P0.05)。T1、T2时C组IL-2浓度明显低于T0时和D组,T2、T3时C组IL-10浓度明显高于T0时和D组(P0.05)。T2、T3时两组Cor、ALD、ACTH水平明显高于T0时,D组Cor、ALD、ACTH水平明显低于C组(P0.05)。Ta、T1、Tb时C组SBP、DBP、CVP明显高于T0时和D组(P0.05)。结论全麻下行肝癌切除术的肝炎肝硬化患者在术后存在一定程度的免疫抑制,静脉泵注右美托咪定可以抑制围术期的应激反应,降低对免疫功能的影响。     

阿魏酸对家兔脊髓缺血再灌注损伤的防治作用

目的　研究阿魏酸对家兔肾下主动脉阻断所致脊髓损害的防治作用及其机理。方法家兔 2 4只 ,随机分为假手术组 (A组 ) ,缺血再灌注损伤组 (B组 )及阿魏酸组 (C组 ) ,每组 8只。B、C组肾下主动脉阻断 4 0分钟后开放 ,再灌注 7天。C组于阻断前 15分钟一次性静注阿魏酸 5 0mg/kg ,余两组则以同样方法静注等容量生理盐水作对照。测定阻断前 (C0 )、开放前 (C40 )、开放后 6 0分钟(R60 )及 7天 (R7d)血清中MDA、SOD、S10 0蛋白、TNFα、IL 1β的含量 ;术后观察后肢神经功能和脊髓形态学变化。结果　 (1)B组缺血及再灌注后血清MDA、S10 0蛋白、TNFα、IL 1β含量明显高于C0点及A组值 (P <0 0 1) ;C组明显低于B组 (P <0 0 1) ,与A组无显著性差异。 (2 )B组缺血及再灌注后SOD活力明显低于C0 点及A组值 (P <0 0 1) ;C组明显高于B组 (P <0 0 1) ,与A组无显著性差异。 (3)C组瘫痪发生率明显低于B组 (P <0 0 1) ,其后肢神经功能评分显著高于B组 (P <0 0 1)。 (4)B组脊髓病理变化较重 ,可见大量神经元坏死 ;C组偶有神经元坏死。结论　预防性静注阿魏酸对家兔主动脉阻断所致脊髓损害有良好的防治作用。其机理与阿魏酸抗氧化、抗炎及抑制TNFα、IL 1β水平升高有关     

硫喷妥钠与异丙酚在小儿心脏手术深低温停循环期间对脑缺血再灌注损伤的影响

目的 观察婴幼儿先天性心脏病心内直视手术,深低温停循环期间给予硫喷妥钠、异丙酚对脑缺血再灌注损伤的影响。方法20例室间隔缺损伴肺动脉高压(VSD+PH)患儿随机分为硫喷妥钠5mg·kg-1(A组)、异丙酚2mg·kg-1(B组)和对照(C组)三组,于转流前(Ⅰ朗)、停循环时(Ⅱ期)、再灌注始(Ⅲ期)及术后24h(Ⅳ期)分别抽取颈内静脉、桡动脉血样做血气分析,并测定乳酸含量(LAC)及肌酸激酶BB(CKBB)和神经特异性烯醇化酶(NSE)的含量;计算脑动静脉氧含量差(Ca-vO2)、脑氧摄取率(Co2ER)。结果 Ⅲ期各组LAC水平最高,并以A组较为明显;脑氧代谢在Ⅱ期各组Ca-vO2、CO2ER均较其余各期低,其中B组下降最为明显,其次为A组和C组;Ⅳ期时,各组Ca-vO2、CO2ER均有所恢复。 各组在Ⅲ期CDBB和Ⅲ、Ⅳ期NSE均有上升趋势,B组增高幅度最低。结论 异丙酚用于深低温停循环期间对脑缺血再灌注损伤有保护作用。     

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.     

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.     

Immunomodulation in Transplantation with Photopheresis

Abstract: Photopheresis is a technique in which peripheral blood mononuclear cells, in the presence of a photoacti-vatable compound, are exposed extracorporeally to ultraviolet A light and reinfused, inducing a host autoregula-tory immune response. Experimental work and ongoing clinical studies are helping to define the role of this novel, safe, and non-toxic immunomodulating technology in the field of transplantation.