丙泊酚预处理对大鼠心肌缺血/再灌注损伤中自噬潮的影响

目的 研究丙泊酚预处理对大鼠心肌缺血/再灌注(ischemia/reperfusion,I/R)期间自噬潮的影响及其机制. 方法 采用大鼠在体心肌I/R损伤模型,将90只雄性SD大鼠按照随机数字表法分为5组(每组18只):①假手术组(Sham组),只穿线不结扎;②I/R组;③丙泊酚预处理组(P+I/R组);④Ⅰ型磷脂酰肌醇3-激酶(phosphatidylinositol 3-kinase,PI3K)抑制剂A66预处理组(A+I/R组);⑤丙泊酚+A66预处理组(P+A+I/R组).采用结扎冠状动脉左前降支的方法制备心肌I/R模型.除Sham组外,其余各组均缺血30 min,再灌注120 min.缺血前15 min,P+I/R组通过股静脉输注丙泊酚15 mg·kg1·h1;A+I/R组缺血前1h腹腔注射A66溶液10 mg/kg;P+A+I/R组在缺血前1h腹腔注射A66溶液10 mg/kg,缺血前15 min再通过股静脉输注丙泊酚15 mg·kg1·h-1.模型制备后取心肌,2,3,5-氯化三苯基四氮唑(2,3,5-triphenyhetrazolium chloride,TTC)法染色并计算梗死面积百分比,酶标法测定乳酸脱氢酶(lactate dehydwgenase,LDH)活性,Western bolt法检测微管相关蛋白1轻链3(microtubule-associated protein 1 light chain 3,LC3)-Ⅱ、P62蛋白的表达量,电子显微镜定性观察自噬体、自噬溶酶体的数量.结果 与I/R组比较,P+I/R组与P+A+I/R组梗死面积[(50.1±-3.9)％比(26.5±1.3)％、(42.6±1.9)％]显著减小(P＜0.05),血清LDH活性降低,LC3-Ⅱ表达水平降低,P62表达水平升高(P＜0.05),自噬体、自噬溶酶体明显减少.与P+I/R组比较,P+A+I/R组梗死面积[(26.5±1.3)％比(42.6±1.9)％]显著增加(P＜0.05),血清LDH活性升高,LC3-Ⅱ表达水平升高,P62表达水平降低(P＜0.05),自噬体、自噬溶酶体增加. 结论 丙泊酚预处理激活PI3K/蛋白激酶B(pmtein kinase B,Akt)通路,抑制I/R心肌中自噬潮进行,对大鼠心肌I/R损伤产生保护作用.     

调控自噬流对巨噬细胞粘附与迁移功能的影响

目的巨噬细胞浸润是包括糖尿病肾病(diabetic nephropathy, DN)在内的多种慢性肾脏疾病的重要组织病理特征。本研究通过调控巨噬细胞(RAW264.7)自噬流各阶段,探究其对巨噬细胞黏附迁移功能的影响。 方法体内实验,建立糖尿病肾病大鼠模型,于12周末分别处死正常大鼠、DN组大鼠,病理染色观察肾脏病理改变,检测肾组织巨噬细胞标志物及自噬相关标志物表达。体外实验,检测正常与高糖(30 mM)条件下,巨噬细胞自噬体数量变化,LC3、Beclin－1(自噬相关标志物)、P62(自噬体清除指标)的表达,以及巨噬细胞粘附迁移数量。分别加用自噬溶酶体降解抑制剂氯喹(CQ)、自噬体生成激活剂雷帕霉素(RAPA),观察其对巨噬细胞自噬标记物表达及其粘附迁移功能的影响,电镜观察巨噬细胞自噬体数量与自噬溶酶体形态的变化。 结果体内实验,DN大鼠肾脏损伤明显,肾小球体积增大,基底膜增厚,系膜基质增多,肾组织CD68(巨噬细胞标志物)、P62表达增加(t＝3.35、t＝16.27, P<0.05),LC3表达减少(t＝51.12, P<0.05);体外实验,在高糖组,电镜观察发现自噬体数量较正常组减少,Western印迹与免疫荧光显示自噬相关蛋白LC3、Beclin－1表达降低,P62表达升高(t＝27.02,t＝45.56、t＝32.71,P<0.05),巨噬细胞粘附和迁移数量增多(t＝6.87、t＝8.76,P<0.05)。用CQ处理后,电镜观察发现巨噬细胞自噬体溶酶体降解受到抑制,Western印迹与免疫荧光显示自噬相关蛋白LC3、Beclin－1表达降低,P62表达升高(t＝14.64、t＝12.45、t＝8.57,P<0.05);CQ进一步促进高糖诱导的巨噬细胞黏附迁移数量增多(t＝4.37、t＝7.27,P<0.05);RAPA增加巨噬细胞自噬体数量,Western与免疫荧光显示RAPA提高了被高糖抑制的巨噬细胞自噬水平,[LC3、Beclin－1表达升高,P62表达降低(t＝9.37、t＝11.53,t＝8.73;P<0.05)],减少高糖诱导的巨噬细胞黏附、迁移数量增多(t＝4.16、t＝5.74, P<0.05)。 结论高糖抑制自噬水平,促进巨噬细胞黏附迁移;抑制自噬溶酶体降解可降低自噬水平、促进巨噬细胞粘附迁移;激活自噬体生成能提高自噬水平,减轻巨噬细胞粘附迁移。     

B淋巴细胞瘤-2蛋白多位点磷酸化在大鼠脊髓损伤后细胞自噬中的表达研究

目的探讨大鼠脊髓损伤(spinal cord injury,SCI)后细胞自噬的变化及其与B淋巴细胞瘤-2(Bcell lymphoma-2,Bcl-2)蛋白多位点磷酸化的关系。方法取40只8周龄雄性SD大鼠,采用改良Allen法制备SCI模型;将造模成功的36只大鼠随机分为SCI组、自噬抑制剂组、自噬促进剂组,每组12只。另取12只大鼠仅切除椎板、不损伤脊髓,作为假手术组。造模结束后,自噬抑制剂组及自噬促进剂组分别于脊髓鞘内注射20μL600 nmol/L 3-甲基腺嘌呤、25 nmol/L雷帕霉素,假手术组及SCI组仅注射20μL生理盐水;每天1次,连续4周。造模后1 d及1、2、4周,采用BBB评分法评价各组大鼠后肢运动功能。末次注射后24 h处死各组大鼠并取脊髓组织,ELISA法检测脊髓组织中过氧化物酶(myeloperoxidase,MPO)活性及TNF-α、IL-1β水平;HE染色观察脊髓组织形态学变化;透射电镜观察脊髓组织中线粒体超微结构变化;免疫荧光染色检测自噬相关蛋白(Beclin1)、微管相关蛋白轻链3(microtubule-associated protein light chain 3,LC3)蛋白表达;TUNEL染色观察脊髓组织神经细胞凋亡;免疫荧光双染检测LC3/TUNEL阳性细胞表达;Western blot检测细胞Bcl-2相关X蛋白(Bcl-2 associated X protein,Bax)、Bcl-2及p-Bcl-2(Ser87)、p-Bcl-2(Ser70)蛋白表达。结果与假手术组相比,SCI组各时间点BBB评分降低,MPO活性、TNF-α、IL-1β水平升高;神经细胞周围间隙增大,细胞肿胀、出现空泡,线粒体中出现自噬小体;Beclin1及LC3蛋白阳性率、神经细胞凋亡率显著升高;LC3、TUNEL阳性细胞增多;Bax、p-Bcl-2(Ser87)、p-Bcl-2(Ser70)蛋白表达升高,Bcl-2蛋白表达降低;以上指标比较差异均有统计学意义(P0.05)。与SCI组相比,自噬抑制剂组各时间点BBB评分降低,MPO活性、TNF-α、IL-1β水平升高;线粒体中出现少量自噬囊泡;Beclin1及LC3蛋白阳性率降低,神经细胞凋亡率显著升高;LC3阳性细胞减少、TUNEL阳性细胞增多;Bax、p-Bcl-2(Ser87)、p-Bcl-2(Ser70)蛋白表达升高,Bcl-2蛋白表达降低。而自噬促进剂组结果与自噬抑制剂组相反;以上指标组间比较差异均有统计学意义(P0.05)。结论大鼠SCI后通过诱导细胞自噬可降低神经细胞凋亡,保护脊髓功能,其机制可能与抑制Bcl-2蛋白多位点磷酸化有关。     

HIF-1α介导缺氧环境下肝癌Bel-7402细胞自噬的激活

目的:探讨缺氧环境肝癌细胞自噬的激活与H IF-1α的关系。方法:将肝癌B el-7402细胞分为常氧组、缺氧+C on sh R N A组和缺氧+H IF-1αsh R N A组,将慢病毒介导的H IF-1αsh R N A转染细胞,继续培养36 h,W estern blot检测H IF-1α蛋白表达;吖啶橙(A O)荧光染色检测自噬溶酶体的形成,丹酰尸胺(M D C)荧光染色检测自噬小体的形成,并应用流式细胞技术定量自噬溶酶体或者自噬小体的荧光强度;W estern blot检测自噬激活的标志蛋白LC 3-Ⅱ表达。结果:慢病毒介导的H IF-1αsh R N A降低了缺氧诱导的肝癌细胞中H IF-1α蛋白的生成(缺氧+H IF-1αsh R N A组vs缺氧+C on sh R N A组,P0.01),H IF-1α降低后,细胞中自噬小体及自噬溶酶体明显减少(缺氧+H IF-1αsh R N A组vs缺氧+C on sh R N A组,P0.01),自噬激活标志蛋白LC 3-Ⅱ明显减少(缺氧+H IF-1αsh R N A组vs C on sh R N A组,P0.01)。结论:缺氧环境下H IF-1α介导了肝癌细胞自噬的激活。     

七氟醚预处理对大鼠脊髓缺血再灌注损伤的影响及自噬在其中的作用

目的 评价七氟醚预处理对大鼠脊髓缺血再灌注损伤的影响及自噬在其中的作用.方法 成年雄性SD大鼠45只,体重420～450 g,采用随机数字表法分为5组(n=9):对照组(Con组)、脊髓缺血再灌注组(I/R组)、七氟醚预处理组(Sevo组)、特异性自噬抑制剂3-甲基腺嘌呤组(3-MA组)和3-MA+七氟醚预处理组(3-MA+ Sevo组).I/R组胸主动脉球囊阻断+体循环低血压制备大鼠脊髓缺血再灌注模型,Sevo组于缺血前24h时吸入3.4％七氟醚2h,3-MA组和3-MA+ Sevo组分别于再灌注即刻和吸入七氟醚前15 min时鞘内注射20出3-MA(10 mmol/L).于再灌注24h时采用神经功能缺陷评分(NDS评分)法评价大鼠神经功能,随后处死取脊髓,Western blot法检测LC3B、Beclin 1、Bcl-2蛋白的表达水平.结果 与Con组比较,I/R组脊髓LC3B、Beclin 1蛋白表达上调,Bcl-2蛋白表达下调,NDS评分升高(P＜0.05);与I/R组比较,Sevo组、3-MA组和3-MA+ Sevo组脊髓LC3B、Beclin 1蛋白表达下调,Bcl-2蛋白表达上调,NDS评分降低(P＜0.05);Sevo组、3-MA组和3-MA+ Sevo组各指标比较差异无统计学意义(P＞0.05).结论 七氟醚预处理可减轻大鼠脊髓缺血再灌注损伤,其机制可能与上调Bcl-2,抑制自噬溶酶体途径,减轻自噬有关.     

自噬相关哺乳动物雷帕霉素靶蛋白信号通路在脊髓损伤中的作用研究进展

<正>脊髓损伤(SCI)可导致严重且不可逆的神经功能缺损甚至终身瘫痪,其常见病因包括交通事故、坠落伤及重物砸伤等。SCI造成的神经系统创伤至今仍是脊柱外科的治疗难题。自噬是一种主要依赖溶酶体介导的分解代谢途径,可使功能失调的细胞成分降解以应对各种形式的压力^[1]。微管相关蛋白1轻链3Ⅱ(LC3Ⅱ)、Beclin-1和p62被认为是自噬的3种标志物,自噬通量的高低可以通过自噬标志物的水平来评估,LC3Ⅱ或LC3Ⅱ/LC3Ⅰ比值、Beclin-1增加以及p62蛋白表达减少都可以表明自噬水平上升^[2]。哺乳动物雷帕霉素靶蛋白(mTOR)是一种丝氨酸/苏氨酸蛋白激酶,是信号网络的核心和细胞生长的中央控制器,它在调节细胞代谢、死亡、存活和增殖方面发挥着重要作用,被认为是自噬的主要负调节因子^[3]。     

晚期糖基化终末产物通过Wnt/β-catenin信号通路调控足细胞自噬和迁移

目的探讨晚期糖基化终末产物(AGEs)诱导Wnt/β-catenin信号通路活化对足细胞自噬和迁移的影响。方法将小鼠永生化肾足细胞系分为牛血清白蛋白组(100mg/L BSA)、糖基化终末产物组(100 mg/L BSA-AGEs)和糖基化终末产物+DKK-1组(100mg/L BSA-AGEs+100 DKK-1 mg/L),以未加干涉的正常足细胞为对照组。Western blot检测足细胞β-catenin蛋白、自噬膜蛋白微管相关蛋白轻链3-II(LC3-Ⅱ)以及自噬底物p62蛋白表达水平,免疫荧光观察足细胞自噬情况,ELISA检测细胞上清液中Nephrin蛋白含量,划痕试验检测足细胞迁移能力。用AGEs和AGEs+RAGE(糖基化终末产物受体)中和抗体处理足细胞系,Western blot检测足细胞β-catenin蛋白的表达。结果与对照组相比,AGEs组p-β-catenin、p62表达升高(P0.05),LC3-Ⅱ表达降低(P0.05)。AGEs+DKK-1组p-β-catenin、p62蛋白表达较AGEs组降低,LC3-Ⅱ表达升高(P0.05),但与对照组比较差异无显著性(P0.05)。BSA组各指标与对照组均无显著性差异(P0.05)。免疫荧光检测发现AGEs组足细胞中LC3荧光强度较对照组明显减弱,AGEs+DKK-1组较AGEs组LC3荧光强度增强,BSA组与对照组比较差异无显著性(P0.05)。AGEs组细胞培养上清中Nephrin含量较对照组明显降低(P0.05),AGEs+DKK-1组较AGEs组升高(P0.05),但仍低于对照组(P0.05),BSA组与对照组差异无显著性(P0.05)。与对照组相比,AGEs组足细胞迁移能力降低(P0.05),AGEs+DKK-1组、BSA组与对照组比较,差异无显著性(P0.05)。AGEs+RAGE中和抗体处理的足细胞β-catenin蛋白水平较AGEs组显著降低(P0.05)。结论 AGEs通过RAGE激活Wnt/β-catenin信号通路,抑制足细胞自噬和迁移能力,可能是糖尿病患者足细胞损伤机制之一,在糖尿病肾病的发生和进展中发挥重要调控作用。     

仙茅苷调节lncRNA MEG3/miR-181a-5p通路对骨质疏松大鼠成骨细胞自噬的影响

目的 探讨仙茅苷（Curculigoside，CUR）对骨质疏松症（osteoporosis，OP）大鼠成骨细胞自噬的影响以及对lncRNA MEG3/miR-181a-5p信号轴的调节作用。方法 体外培养骨髓间充质干细胞（BM-MSCs）诱导成骨细胞分化，CCK-8法筛选CUR浓度；数据库预测lncRNA MEG3与miR-181a-5p结合位点；利用转染技术将BM-MSCs细胞分为NC组、CUR组、CUR+3-MA组、CUR+pc-NC组和CUR+pc-LncRNA MEG3组，qRT-PCR检测lncRNA MEG3、miR-181a-5p的表达水平，碱性磷酸酶（ALP）染色法检测细胞ALP活性，MDC法检测细胞自噬体数量，免疫荧光检测细胞微管相关蛋白1-轻链3（LC3）、自噬效应蛋白（Beclin1）的表达。肌肉注射地塞米松磷酸钠建立OP大鼠，大鼠分为对照组（CT组）、模型组（OP组）、OP+CUR组（灌胃15 mg/kg CUR），CT检测大鼠胫骨骨形态学，Western blot和qRT-PCR分别检测LC3Ⅱ/Ⅰ、Beclin1与lncRNA MEG3、miR-181a-5的表达。结果 25 μg/mL以上浓度的CUR显著提高BM-MSCs细胞增殖活力（P＜0.05）；lncRNA MEG3与miR-181a-5p具有靶向结合位点；与NC组相比，CUR组细胞ALP活性、自噬体数量以及LC3、Beclin1表达增加（P＜0.05）；与CUR组相比，CUR+3-MA组细胞ALP活性、自噬体数量以及LC3、Beclin1表达减少（P＜0.05）；与CUR+pc-NC组相比，CUR+pc-LncRNA MEG3组细胞ALP活性、自噬体数量以及LC3、Beclin1表达减少（P＜0.05）。OP组大鼠骨形态学评价以及LC3Ⅱ/Ⅰ、Beclin1、miR-181a-5p表达较CT组下降，lncRNA MEG3表达增加（P < 0.05）；OP+ CUR组大鼠骨形态学评价以及LC3Ⅱ/Ⅰ、Beclin1、miR-181a-5p表达较OP组增加，lncRNA MEG3表达降低（P＜0.05）。结论 CUR可能通过调节LncRNA MEG3/miR-181a-5p信号轴促进OP大鼠成骨细胞自噬活性。     

脊髓背角自噬与大鼠吗啡耐受形成的关系

目的 探讨脊髓背角自噬与大鼠吗啡耐受形成的关系.方法 雄性成年SD大鼠,体重250～ 300 g,取鞘内置管成功的大鼠24只,采用随机数字表法,将其分为3组(n=8):对照组(C组)、吗啡耐受组(M组)和吗啡+自噬增强剂雷帕霉素组(MR组).采用鞘内注射吗啡20 μg,2次/d,连续7d的方法制备吗啡耐受模型.C组给予等容量生理盐水.MR组鞘内注射吗啡20 μg,2次/d,连续7d,并于第3天第2次注射吗啡同时鞘内注射雷帕霉素2.3μg,连续3d.于鞘内注射前及第1、3、5、7天第2次鞘内注射后30 min测定机械缩足反应阈(MWT).最后1次MWT测定结束后1h取L4-6段脊髓背角,采用Western blot法测定总哺乳动物雷帕霉素靶蛋白(mTOR)和磷酸化mTOR(p-mTOR)及自噬标记蛋白LC3Ⅱ的表达.以p-mTOR占总mTOR表达水平的百分比反映mTOR的活性.结果 随鞘内注射时间延长,M组和MR组MWT逐渐降低(P＜0.05);与C组比较,M组和MR组鞘内注射期间MWT升高,脊髓背角mTOR活性降低,LC3Ⅱ表达上调(P＜0.05);与M组比较,MR组鞘内注射第3、5、7天MWT升高,脊髓背角mTOR活性降低,LC3Ⅱ表达上调(P＜0.05).结论 脊髓背角自噬增强是吗啡耐受形成时机体的适应性调节机制,可延缓吗啡耐受形成.     

核苷酸结合寡聚化结构域样受体蛋白3炎性小体在心肺转流大鼠围术期神经认知障碍中的作用

目的探讨核苷酸结合寡聚化结构域样受体蛋白3(NLRP3)炎性小体在心肺转流(CPB)大鼠围术期神经认知障碍(PND)中的作用。方法成年雄性SD大鼠30只,体重350～450 g,进行Morris水迷宫训练5 d后随机分为三组,每组10只:假手术组(S组)、CPB组(C组)和CPB+NLRP3炎性小体抑制剂Ac-YVAD-cmk组(Y组)。S组进行双侧隐动脉、右大隐静脉和右颈内静脉穿刺置管,但不进行CPB;C组穿刺置管后行CPB 60 min;Y组在CPB前30 min给予Ac-YVAD-cmk 8 mg/kg腹腔注射,穿刺置管后行CPB 60 min。术后第3天采用Morris水迷宫实验评估大鼠认知功能,ELISA法检测血浆和海马组织IL-1β和IL-18浓度,Western blot法检测海马组织NLRP3、凋亡相关点样蛋白(ASC)和半胱氨酸蛋白水解酶-1前体(pro-caspase-1)蛋白含量,TUNEL法检测海马组织凋亡情况,计算凋亡指数。结果与S组比较,C组和Y组逃避潜伏期明显延长(P0.05),120 s穿越原平台次数明显减少(P0.05),血浆和海马组织IL-1β和IL-18浓度、NLRP3、ASC和pro-caspase-1蛋白含量以及凋亡指数明显升高(P0.05)。与C组比较,Y组逃避潜伏期明显缩短(P0.05),120 s穿越原平台次数明显增多(P0.05),血浆和海马组织IL-1β和IL-18浓度、NLRP3、ASC和pro-caspase-1蛋白含量以及凋亡指数明显降低(P0.05)。结论 CPB后大鼠PND可能与NLRP3炎性小体的激活有关,使用NLRP3炎性小体抑制剂可减轻大鼠PND的发生。     

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.     

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.     

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.     

Dilemma of Membrane Biocompatibility and Reuse

Abstract: Numerous articles have been published on the multiple use of dialyzers and on the effect of different reprocessing chemicals and techniques on the dialyzer biocompatibility and performance. The results often appear contradictory, especially those comparing standard biocompatibility parameters. Despite this confusion, a discerning review of the published works allows certain limited conclusions to be drawn. Reprocessing of used hemodialyzers changes the biocompatibility profile of a dialyzer as defined by the parameters complement activation. leukopenia, and cytokine release. The effect of reprocessing depends on the chemicals and reprocessing technique applied and also on the type of membrane polymer being subjected to the reprocessing procedure. Reports of pyrogenic reactions indicate that the flux of the membrane also influences how suitable it is for safe reuse. An increased risk of allergic and pyrogenic reactions appears to be associated with dialyzer reuse. Furthermore, there has been a lack of investigations into the immunologic effect of the layer of adsorbed and chemically altered proteins that remains on the inner surface of reprocessed dialyzers. We conclude that the clinical benefit of dialyzer reuse cannot be generally accepted from a biocompatibility point of view.     

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.