PI3K/Akt信号通路在异丙酚后处理减轻大鼠心肌细胞缺氧复氧损伤中的作用

目的 评价磷脂酰肌醇3-激酶/丝氨酸-苏氨酸蛋白激酶(PI3K/Akt)信号通路在异丙酚后处理减轻大鼠心肌细胞缺氧复氧损伤中的作用.方法 体外培养SD乳鼠心肌细胞,接种于96孔板(细胞密度1×105/ml,200 μl/孔)或6孔板(细胞密度5×105/ml,2 ml/孔)中,采用随机数字表法,将细胞随机分为4组(n=24):常规培养组(C组)细胞常规培养6h;缺氧复氧组(H/R组)细胞行缺氧2h,复氧4h;缺氧复氧+异丙酚组(H/R+P组)于缺氧结束时行异丙酚(终浓度50 μmol/L)后处理;H/R+异丙酚+ PI3K抑制剂组(H/R+ P+W组)于缺氧结束时加入PI3K抑制剂渥曼青霉素(终浓度100nmol/L)和异丙酚(终浓度为50μmol/L).复氧结束时,采用MTT法测定细胞活力,应用生化自动分析仪测定培养液LDH活性;流式细胞仪检测细胞凋亡情况;Western blot法检测心肌细胞磷酸化Akt(p-Akt)、Bcl-2及Bax表达水平.结果 与C组相比,H/R组细胞活力降低,LDH活性和细胞凋亡率升高,p-Akt和Bax表达上调,Bcl-2表达下调,Bcl-2/Bax降低(P＜0.05).与H/R组比较,H/R+P组细胞活力升高,LDH活性和细胞凋亡率降低,p-Akt和Bcl-2表达上调,Bax表达下调,Bcl-2/Bax升高(P＜0.05).与H/R+P组比较,H/R+ P+W组细胞活力降低,LDH活性和细胞凋亡率升高,p-Akt和Bcl-2表达下调,Bcl-2/Bax降低(P＜0.05).结论 异丙酚后处理减轻心肌细胞缺氧复氧损伤的机制与激活PI3K/Akt信号通路有关.     

地氟醚预处理与缺氧/复氧损伤内皮细胞凋亡相关基因表达

目的 观察地氟醚预处理对缺氧/复氧(A/R)损伤内皮细胞凋亡相关基因Bcl-2及Bax表达的影响.探讨地氟醚预处理抑制细胞凋亡的机制.方法 选用人脐静脉内皮细胞株(ECV304).将细胞分为五组,即A/R组(A组)、A/R 肿瘤坏死因子α(TNF-α)10 ng/ml组(B组)、地氟醚1.0MAC预处理 A/R组(C组)、地氟醚1.0 MAC预处理 A/R TNF-α 10 ng/ml组(D组)和空白对照组(E组).应用Real-time PCR、Western Blot方法检测各组细胞中Bcl-2及Bax mRNA和蛋白水平.结果 Real-time PCR和Western Blot结果提示,与E组相比,A、B组Bcl-2表达降低,Bax表达升高(P<0.05或P<0.01).经地氟醚预处理后,C、D组细胞较相应未经预处理的A、B组Bcl-2表达增加.Bax表达降低(P<0.05或P<0.01).结论 地氟醚预处理可通过调节Bcl-2及Bax的表达来抑制缺氧/复氧所引起的内皮细胞凋亡.     

内质网应激在高糖培养加重神经细胞缺氧-复氧损伤中的作用

目的研究内质网应激在高糖培养加重神经细胞缺氧-复氧损伤中的作用。方法在含10%胎牛血清的DMEM/F12培养基中培养小鼠神经瘤母细胞N2a,按照接种密度每毫升105个将细胞接种于培养板中。采用随机数字分组法将细胞分为四组:正常糖对照组(NC组)、正常糖缺氧-复氧组(NH组)、高糖对照组(HC组)、高糖缺氧-复氧组(HH组)。待细胞贴壁后,将DMEM/F12培养基更换为高糖培养基,孵育48h,造高糖孵育模型。在缺氧小室中缺氧3h后,再转入正常氧孵育箱中复氧2h,造缺氧-复氧损伤模型。NC组未作处理;NH组行缺氧-复氧处理;HC组行高糖孵育处理;HH组先行高糖孵育48h后,再作缺氧-复氧处理。采用CCK-8法检测细胞活力,流式细胞仪检测细胞凋亡率,Western blot法检测细胞GRP78、CHOP蛋白含量。结果与NC组和HC组比较,NH组和HH组细胞活力明显减弱,凋亡率明显升高,GRP78、CHOP蛋白含量明显增多(P0.01);与NH组比较,HH组细胞活力明显减弱,凋亡率明显升高,GRP78、CHOP蛋白含量明显增多(P0.05)。结论高糖培养加重神经细胞缺氧-复氧损伤,可能与内质网应激标志性蛋白GRP78蛋白含量增多和促凋亡转录因子CHOP介导的细胞凋亡相关。     

不同浓度七氟醚预处理对大鼠海马神经元缺氧复氧时细胞凋亡的影响及线粒体ATP敏感型钾通道在其中的作用

目的 探讨不同浓度七氟醚预处理对大鼠海马神经元缺氧复氧时细胞凋亡的影响及线粒体ATP敏感型钾通道(mito-KATP通道)在其中的作用.方法 新生(出生＜24 h)SD大鼠,雌雄不拘,体重5～6 g,原代培养海马神经元,接种于培养孔或培养皿中,采用随机数字表法,将其随机分为7组,每组48孔和12皿,正常对照组(C组):不予任何处理;缺氧复氧组(HR组):缺氧4 h复氧24 h;6%七氟醚预处理组(S1 组)、4%七氟醚预处理组(S2 组)、2%七氟醚预处理组(S3 组):分别经6%、4%、2%七氟醚预处理后行缺氧复氧;5-羟葵酸100 μmol/L预处理组(5-HD组):经mito-KATP通道阻断剂5-羟葵酸(终浓度100 μmol/L)预处理后进行缺氧复氧;5-羟葵酸100 μmol/L+6%七氟醚预处理组(5-HD+S组):同时行5-羟葵酸和6%七氟醚预处理后进行缺氧复氧.各组以上处理结束后,测定神经元活力、凋亡率、Bcl-2和Bax蛋白的表达水平.结果 与C组比较,其余6组海马神经元活力降低,细胞凋亡率升高,Bcl-2和Bax蛋白表达上调(P＜0.01);与HR组比较,S1组～S3组海马神经元活力增强,细胞凋亡率降低,Bcl-2蛋白表达上调,Bax蛋白表达下调(P＜0.01),5-HD组和5-HD+S组上述指标比较差异无统计学意义(P＞0.05);与S1组比较,S2组、S3组和5-HD+S组海马神经元活力降低,细胞凋亡率升高,Bcl-2蛋白表达下调,Bax蛋白表达上调(P＜0.01);与S2组比较,S3组海马神经元活力降低,细胞凋亡率升高,Bcl-2蛋白表达下调,Bax蛋白表达上调(P＜0.01).结论 七氟醚预处理可抑制大鼠海马神经元缺氧复氧时细胞凋亡,从而减轻神经元损伤,且呈浓度依赖性,机制可能与开放神经元mito-KATP通道,上调Bcl-2蛋白表达,下调Bax蛋白表达有关.

Abstract：

Objective To investigate the effect of preconditioning with different concentrations of sevoflurane on hypoxia-reoxygenation(H/R)-induced apoptosis in rat hippocampal neurons and the role of mitochondrial KATP(mito-KATP)channels.Methods Primary cultured hippocampal neurons isolated from newborn SD rats(＜24h)of both sexes,weighing 5-6 g,were randomly divided into 7 groups with 48 wells and 12 dishes in each one:control group(C group),H/R group,preconditioning with 6%,4%and 2% sevoflurane groups(S1-3 groups),5-hydroxydecanoate(5-HD,mito-KATP channel blocker)100 μmol/L preconditioning group(5-HD group)and preconditioning with 5-HD 100 μmol/L+6% sevoflurane group(5-HD+S group).The neurons were exposed to 4 h hypoxia followed by 24 h reoxygenation. In S1-3 groups, preconditioning was performed with 6% , 4% and 2% sevoflurane respectively before H/R. In 5-HD group, preconditioning was performed with 5-HD (final concentration 100 μmol/L) before H/R. In 5-HD + S group, preconditioning was performed with 5-HD 100 μmol/L and 6% sevoflurane before H/R. The neuronal viability, apoptosis rate and expression of Bcl-2 and Bax were determined after 24 h reoxygenation.Results The neuronal viability was significantly lower,while the apoptosis rate and expression of Bcl-2 and Bax were significantly higher in the other 6 groups than in group C(P＜0.01).The neuronal viability and expression of Bcl-2 were significantly higher,while the apoptosis rate and Bax expression were lower in S1-3 groups than in group H/R. There was no significant difference in the parameters mentioned above between 5-HD and 5-HD + S groups(P＞0.05).The neuronal viability and expression of Bcl-2 were significantly lower, while the apoptosis rate and Bax expression were higher in S2, S3 and 5-HD + S groups than in group S1, and in group S3 than in group S2(P＜0.0l) .Conclusion Sevoflurane preconditioning can inhibit H/R-induced apoptosis in rat hippocampal neurons and reduce the injury to neurons in a concentration-dependent manner, and the underlying mechanism may be related to activation of mito-KATP channels, up-regulation of Bcl-2 expression and down-regulation of Bax expression.     

右美托咪定激活Akt通路对缺氧复氧肾小管上皮细胞凋亡的影响

目的 观察右美托咪定对缺氧复氧诱导肾小管上皮细胞凋亡的作用,并探讨其作用机制。方法 将人肾小管上皮细胞分五组干预：对照组(C组),常氧环境中培养28 h;缺氧复氧组(HR组),低氧环境中培养24 h后常氧环境中培养4 h;右美托咪定处理组(D组),复制缺氧复氧模型前以右美托咪定处理2 h;Akt阻断剂Uprosertib处理组(U组),复制缺氧复氧模型前以Akt阻断剂Uprosertib处理1 h;右美托咪定复合Akt阻断剂Uprosertib处理组(DU组),复制缺氧复氧模型前先以Akt阻断剂Uprosertib处理1 h,再以右美托咪定处理2 h。采用Ellsa法检测细胞上清中TNF-ɑ、IL-6、IL-1β浓度,MTT法检测细胞存活率,流式细胞仪检测细胞凋亡率,Western blot法检测Bcl-2、Bax、caspase-3、caspase-9、p-Akt蛋白含量。结果 与C组比较,HR组、D组、U组和DU组TNF-ɑ、IL-6、IL-1β浓度、细胞凋亡率、Bax、caspase-3、caspase-9蛋白含量明显升高(P<0.05),细胞存活率、Bcl-2、p-Akt蛋白含量明显降低(P<0.05)。与HR组比较,D组和DU组TNF-ɑ、IL-6、IL-1β浓度、细胞凋亡率、Bax、caspase-3、caspase-9蛋白含量明显降低(P<0.05),细胞存活率、Bcl-2、p-Akt蛋白含量明显升高(P<0.05);U组TNF-ɑ、IL-6、IL-1β浓度、细胞凋亡率、Bax、caspase-3、caspase-9蛋白含量明显升高(P<0.05),细胞存活率、Bcl-2、p-Akt蛋白含量明显降低(P<0.05)。与D组比较,U组和DU组TNF-ɑ、IL-6、IL-1β浓度、细胞凋亡率、Bax、caspase-3、caspase-9蛋白含量明显升高(P<0.05),细胞存活率、Bcl-2、p-Akt蛋白含量明显降低(P<0.05)。与U组比较,DU组TNF-ɑ、IL-6、IL-1β浓度、细胞凋亡率、Bax、caspase-3、caspase-9蛋白含量明显降低(P<0.05),细胞存活率、Bcl-2、p-Akt蛋白含量明显升高(P<0.05)。结论 右美托咪定可通过激活Akt信号通路,抑制缺氧复氧造成的肾小管上皮细胞凋亡,发挥保护作用。     

二氮嗪后处理对缺氧/复氧成年大鼠心肌细胞存活率及磷酸化糖原合成激酶-3β、Bcl-2和Bax表达的影响

目的 研究线粒体ATP-敏感性钾通道(mitochondrial ATP-sensitive potassium channel,mitoKATP通道)开放剂二氮嗪(diazoxide,DZ)后处理对成年大鼠心肌细胞缺氧/复氧(hypoxia/reoxygenation,H/R)后细胞存活及对磷酸化糖原合成激酶-3β(phospho glycogen synthase kinase-3β,pGSK-3β),Bcl-2,Bax表达的影响. 方法 体外培养原代成年大鼠(30只)心肌细胞建立H/R损伤模型,按随机数字表法随机分为5组(每组6只):①Normal组:在二氧化碳(CO2)培养箱中持续培养6h组;②H/R组:缺氧3h复氧3h组;③DZ组:缺氧3h复氧3h,复氧5 min时给予100 μmol/L DZ组;④DZ+5-HD组:缺氧3h复氧3h,缺氧末给予100 μmol/L 5-羟葵酸盐(5-hydroxydecanoate,5-HD),复氧5 min时给予100μmol/L DZ组;⑤5-HD组:缺氧3h复氧3h,缺氧末给予100 μmol/L 5-HD组.复氧3h末通过计数细胞长杆率测定存活率,免疫印迹法测定心肌细胞内pGSK4β,Bcl-2和Bax的表达. 结果 复氧3h末,Normal组单个心肌细胞收缩幅度为(13.12±0.19)％,与Normal组比较,其他各组单个心肌细胞收缩幅度明显降低[H/R组为(7.97±0.22)％,DZ组为(10.48±0.20)％,DZ+5-HD组为(7.97±0.19)％,5-HD组为(8.22±0.22)％](P＞0.05),心肌细胞内Bcl-2表达水平降低,Bax表达水平升高(P＜0.05).DZ后处理组心肌细胞存活率为(64±5)％,与H/R组比较明显增高(P＜0.05),心肌细胞内Bcl-2、pGSK4β表达水平升高,Bax表达水平降低,而缺氧末即刻给予5-HD可以逆转DZ后处理的这些作用(P＜0.05);5-HD组与H/R组比较差异无统计学意义(P＞0.05). 结论 DZ后处理可能通过激活mitoKATP通道、上调pGSK-3β及Bcl-2,下调Bax的表达增加H/R后成年大鼠心肌细胞的存活.     

过度训练可通过破坏Bax/Bcl-2平衡激活caspase依赖的凋亡通路诱导大鼠肾小管上皮细胞凋亡

目的 观察过度训练大鼠肾组织Bax、Bcl-2及 caspase-3的表达及其与肾小管上皮细胞凋亡的关系,探讨caspase依赖的凋亡信号途径在其中的作用及其机制。 方法 将48只雄性Wistar大鼠按随机数字表法分为对照组（CN）、力竭运动组（ES）、旋覆花素干预组（IB）。CN组为安静对照;ES组又根据力竭后恢复时间分为力竭后即刻（ESI）、力竭后6 h（ES 6 h）和力竭后24 h（ES 24 h）组;IB组于力竭运动前24 h 给予旋覆花素25 ml/kg分3次灌胃后进行力竭运动,分为IB 6 h和IB 24 h组。采用大鼠游泳至力竭建立过度训练模型。TUNEL法检测肾小管上皮细胞凋亡。免疫组织化学法检测肾组织Bax、Bcl-2及 caspase-3的表达。Western印迹法测定肾组织caspase-3蛋白的表达。用图像分析系统测定肾小管凋亡细胞、Bax、Bcl-2及 caspase-3表达的平均吸光度并计算Bax和Bcl-2的比值。用Pearson法分析Bax和Bcl-2的比值与caspase-3之间的相关性。用非参Spearman法分析Bax/Bcl-2的比值和caspase-3与细胞凋亡之间的相关性。 结果 TUNEL法显示,过度训练大鼠肾组织凋亡细胞主要分布在肾小管上皮细胞,力竭后即刻、6 h及24 h肾小管上皮细胞凋亡数呈进行性增多（P < 0.01）;免疫组化显示,过度训练大鼠肾组织caspase-3的表达及分布与Bax/Bcl-2比值变化及凋亡细胞的分布一致。图像分析显示,大鼠肾小管上皮细胞Bax/Bcl-2比值与caspase-3的表达于力竭后即刻、力竭后6 h、力竭后24 h逐渐增高（均P < 0.05）,均显著高于对照组（均P < 0.05）。Western 印迹测定结果也显示caspase-3蛋白表达的变化趋势。过度训练大鼠肾小管上皮细胞Bax/Bcl-2比值与caspase-3的表达呈正相关（r = 0.865,P < 0.05）;Bax/Bcl-2比值和caspase-3的表达与肾小管上皮细胞凋亡之间均呈正相关（r = 0.674,r = 0.837,均P < 0.05）。用旋覆花素干预后,过度训练引起的肾小管上皮细胞Bax/Bcl-2比值增高和caspase-3的过度表达及肾小管上皮细胞的过度凋亡均被显著抑制（均P < 0.05）。 结论 过度训练可通过破坏肾小管上皮细胞Bax/Bcl-2的平衡,激活caspase依赖的凋亡信号通路,进而诱导大鼠肾小管上皮细胞凋亡。这可能是过度训练引起肾小管上皮细胞凋亡的分子机制之一。     

瘦素预先给药对L02肝细胞缺氧复氧时细胞凋亡的影响

目的 探讨瘦素预先给药对L02肝细胞缺氧复氧时细胞凋亡的影响.方法 L02肝细胞接种于6孔培养板中,孵育24 h后,随机分为6组,每组6孔:对照组(C组)、缺氧复氧组(HR组)和不同浓度瘦素预处理组(L_(1～4)组).HR组于37℃95%N_2-5%CO_2培养箱中缺氧12 h,然后于37℃95%O_2-5%CO_2培养箱中复氧12 h;L_(1～4)组先分别加入瘦素100、200,400和800 μg/L,再进行缺氧复氧.取细胞上清液,采用赖氏法测定谷丙转氨酶(ALT)和谷草转氨酶(AST)的浓度;采用Hoechst 33342/PI双染色法测定细胞捌亡情况,计算细胞凋亡率;采用荧光定量PCR法测定Bax mRNA和Bcl-2 mRNA的表达.结果 与C组比较,HR组和L_(1～4)组ALT和AST的浓度升高,早期凋亡率和晚期凋亡率升高,Bax mRNA和Bcl-2 mRNA表达上调(P<0.01);与HR组比较,L_(1～4)组ALT和AST的浓度下降,早期凋亡率降低,L_3组Bax mRNA表达下调,L_2组和L_3组Bcl-2 mRNA表达上调(P<0.01);L_(1～4)组间ALT和AST的浓度、早期凋亡率和晚期凋亡率、Bax mRNA和Bcl-2 mRNA表达差异无统计学意义(P>0.05).结论 瘦素预先给药可抑制L02肝细胞缺氧复氧时细胞凋亡,其机制与上调肝细胞Bcl-2 mRNA的表达,下调Bax mRNA的表达有关.     

氢气对PC12细胞缺氧复氧时内质网应激的影响

目的 探讨氧气对PC1 2细胞缺氧复氧时内质网应激的影响.方法 PC12细胞采用随机数字表法,将其随机分为4组,正常对照组:细胞常规培养25 h;阳性对照组:细胞正常培养1h后,用氧气饱和的RPM1-1640培养基继续培养24 h;缺氧复氧组:细胞缺氧1h后复氧24 h;氢气组:细胞缺氧1 h后,州氧气饱和的RPM1,1640培氧基复氧24 h.PC12细胞加入含Na2S2O4终浓度为5.0mmol/L的RPMI-1640培养液,5％ CO2培养箱37 ℃孵育1h;更换正常RPMI-1640培养液,继续培养24h,制备PC12细胞缺氧复氧模型.采用WST-1法测定细胞相对增殖率,采用硫代巴比妥酸法测定MDA浓度,采用免疫组化法检测caspase-3表达,采用RT-PCR法检测活化转录因子4(ATF4)mRNA和C/EBP同源蛋白(CHOP)mRNA的表达.结果 与正常对照组和阳性对照组比较,缺氧复氧组细胞相对增殖率降低,MDA浓度升高,caspase-3、ATF4 mRNA和CHOP mRNA的表达七调,氧气组ATF4 mRNA和CHOP mRNA的表达上调(P＜0.05);正常对照组和阳性对照组间细胞相对增殖率、MDA浓度、caspase-3 、ATF4nRNA和CHOP mRNA的表达比较差异无统计学意义(P＞0.05);与缺氧复氧组比较,氢气组细胞相对增殖率升高,MDA浓度降低,caspase-3、ATF4 mRNA和CHOP mRNA的表达下调(P＜0.05).结论 氧气可能通过抑制内质网应激,降低细胞凋亡,减轻PC12细胞缺氧复氧损伤.     

血红素加氧酶-1在七氟醚预处理减轻乳鼠心肌细胞缺氧复氧损伤中的作用

目的 探讨血红素加氧酶-1(HO-1)在七氟醚预处理减轻乳鼠心肌细胞缺氧复氧损伤中的作用.方法 新生健康清洁级SD大鼠15只,日龄1～3d,处死后取心室肌组织,原代培养心肌细胞,以1×106个/ml接种于6孔培养板或以2× 105个/ml接种于24孔培养板,采用随机数字表法,将其随机分为4组(n＝25):对照组(C组)常规培养;缺氧复氧组(H/R组)采用缺氧2h,复氧1h的方法制备心肌细胞缺氧复氧损伤模型;七氟醚预处理组(S+ H/R组)细胞经2.5％七氟醚预处理20min后行药物洗脱10 min,再行缺氧复氧处理;锌原卟啉+七氟醚预处理组(ZnPP+ S+ H/R组)细胞经HO-1抑制剂锌原卟啉3 μmol/L孵育1h后,行七氟醚预处理及缺氧复氧处理.于复氧结束后测定心肌细胞HO-1表达、细胞凋亡率、细胞内游离Ca2+浓度([Ca2+]i)、线粒体膜通透性转运孔(PTP)开放程度、细胞色素C(Cyto C)表达及培养液LDH和CK活性.结果 与C组比较,H/R组心肌细胞HO-1和胞浆Cyto C表达上调,线粒体Cyto C表达下调,培养液LDH、CK活性、细胞凋亡率、[Ca2+]i和PTP开放度升高(P<0.01).与H/R组比较,S+H/R组心肌细胞HO-1和线粒体Cyto C表达上调,胞浆Cyto C 表达下调,培养液LDH、CK活性、细胞凋亡率、[Ca2+]i和PIP开放度降低(P<0.01).与S+H/R组比较,ZnPP+ S+ H/R组心肌细胞HO-1和线粒体Cyto C表达下调,胞浆CytoC表达上调,培养液LDH、CK活性、细胞凋亡率、[Ca2+]i和PTP开放度升高(P<0.01).结论 HO-1表达上调参与了七氟醚预处理减轻乳鼠心肌细胞缺氧复氧损伤.     

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.     

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.     

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.     

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.     

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.     

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.     

Systemic analgesia adapted to the children's condition

A concept of balanced analgesia using nonsteroidal anti-inflammatory drugs (NSAIDs), paracetamol (acetaminophen), opioids, and corticosteroids can also be used in patients with pre-existing illnesses. NSAIDs are the most effective treatment for acute pain of moderate intensity in children; however, these drugs should be avoided in patients at increased risk for serious side effects, e.g. patients with renal impairment, bleeding tendency, or extreme prematurity. NSAIDs can be given with minimal risks to the younger child with mild to moderate asthma, and, in these patients, the use of steroids can be encouraged; in addition to their antiemetic and analgesic action, a beneficial effect on asthma symptoms can be expected. In the non-intubated child with cerebral trauma, exaggerated sedation caused by opioids and increased bleeding tendency caused by NSAIDs must be avoided. In neonates and small infants, the oral administration of sucrose or glucose is helpful to minimize pain reaction during short uncomfortable interventions.