白细胞介素12在大鼠肺缺血再灌注损伤中的作用

目的 评价白细胞介素12(IL-12)在大鼠肺缺血再灌注损伤中的作用.方法 健康成年雄性SD大鼠24只,8-10周龄,体重250-280 g,采用随机数字表法,将大鼠随机分为3组(n=8):假手术组(S组),肺缺血再灌注损伤组([/R组),IL-12单克隆抗体组(IL-12组).S组只分离肺门不夹闭；I/R组夹闭肺门60 min后,恢复灌注2 h；IL-12组于夹闭肺门前1h尾静脉注射IL-12单克隆抗体200μg/kg.于再灌注结束时采集血样和肺绀织,测定血浆TNF-α浓度、辅助性T细胞(Th)1和Th2水平、肺组织湿干重(W/D)比、髓过氧化物酶(MPO)活性、MDA含量及动脉血氧分压(PaO2)及二氧化碳分压(PaCO2).光镜下观察肺组织病理学改变.结果 与S组比较,I/R组和IL-12组肺组织W/D比、MDA含量、MPO活性、血浆TNF-α浓度升高,I/R组PaO2降低,PaCO2、Th1水平和Th1/Th2升高(P＜0.01),Th2水平差异无统计学意义(P＞0.05),IL-12组PaO2、PaCO2、Th1、Th2水平及Th1/Th2差异无统计学意义(P＞0.05)；与I/R组比较,IL-12组PaCO2、肺组织W/D比、MDA含量、MPO活性、血浆TNF-α浓度、Th1水平和Th1/Th2降低,Th2水平和PaO2升高(P＜0.01).I/R组肺组织损伤明显,IL-12组肺组织损伤程度明显减轻.结论IL-12通过使Tn1/Th2失衡而参与肺缺血再灌注损伤.     

乳化异氟醚对大鼠肺缺血-再灌注内质网应激的影响

目的探索乳化异氟醚预处理对大鼠肺缺血-再灌注损伤诱导内质网应激的影响。方法雄性SD大鼠32只随机分成四组:假手术组(S组)、缺血-再灌注组(IR组)、乳化异氟醚预处理(EI组)、脂肪乳组(IL组)。S组腹腔注射生理盐水10.5ml/kg,24h后仅开胸游离左肺门,不进行阻断左肺门;IR组、EI组和IL组分别腹腔注射生理盐水、8%乳化异氟醚10.5 ml/kg、30%脂肪乳10.5ml/kg,24h后通过阻断左肺门1h后再灌注2h建立大鼠原位肺缺血-再灌注损伤模型。于再灌注2h即刻经左心室采集血样检测PaO2、PaCO2值;取左肺组织测湿重/干重比(W/D),通过HE染色评估肺组织病理损伤程度;通过RT-PCR和Western blot检测肺组织中GRP78和CHOP的表达水平。结果与S组比较,IR组、EI组和IL组PaCO2、肺组织GRP78、CHOP mRNA和CHOP蛋白表达明显升高,PaO2明显降低(P0.05),GRP78蛋白表达水平差异无统计学意义;与IR组比较,EI组、IL组PaCO2、肺组织GRP78mRNA、CHOP mRNA和CHOP蛋白表达明显降低、PaO2明显升高(P0.05),GRP78蛋白表达水平差异无统计学意义。与IL组比较,EI组PaCO2、肺组织W/D、GRP78、CHOP mRNA和CHOP蛋白表达明显降低、PaO2明显升高(P0.05),GRP78蛋白表达水平差异无统计学意义。病理显示EI组和IL组肺损伤轻于IR组,EI组肺损伤轻于IL组。结论乳化异氟醚和脂肪乳预处理均可减轻大鼠术后肺缺血-再灌注损伤引起的过度内质网应激,并且乳化异氟醚的保护效果更显著。     

GSK-3β抑制剂TDZD-8对大鼠肺缺血再灌注时NF-κB活化的影响

目的 评价GSK-3β抑制剂TDZD-8对大鼠肺缺血再灌注时NF-κB活化的影响.方法 健康雄性SD大鼠32只,8～10周龄,体重250 ～ 280 g,采用随机数字表法,将其随机分为4组(n=8):假手术组(sham组)、肺缺血再灌注组(I/R组)、肺缺血再灌注+DMSO组(I/R+ DMSO组)和肺缺血再灌注+ GSK-3β抑制剂TDZD-8组(I/R+ TDZD-8组).采用夹闭左肺门1h恢复灌注的方法制备肺缺血再灌注模型;I/R+ DMSO组和I/R+ TDZD-8组于再灌注前5 min分别于颈外静脉注射10％ DMSO和TDZD-8 1 mg/kg.于再灌注2h时取腹主动脉血测定动脉血氧分压(PaO2)、血浆IL-6和TNF-α浓度;然后处死大鼠,取肺组织测定肺湿干重比(W/D)、髓过氧化物酶(MPO)活性及p-GSK-3β以及p-NF-κBp65的表达,电镜下观察肺组织病理学结果.结果 与sham组比较,其余3组PaO2和肺组织p-GSK-3β表达水平降低,血浆IL-6和TNF-α浓度,肺组织W/D、MPO活性及p-NF-κB p65表达水平升高(P＜0.05),I/R+ TDZD-8组PaO2和P-GSK-3β表达水平升高,上述其余各指标降低(P＜0.05).I/R+ DMSO组与I/R组各指标差异无统计学意义(P＞0.05).I/R+ TDZD-8组肺组织病理学损伤较I/R组减轻.结论 GSK-3β抑制剂TDZD-8可通过下调NF-κB磷酸化抑制炎性反应,从而减轻肺缺血再灌注损伤.     

L-N6-(1-亚氨乙基)赖氨酸对大鼠移植肺缺血再灌注损伤的影响

目的 探讨L-N6-(1-亚氨乙基)赖氨酸(L-NIL)对大鼠移植肺缺血再灌注损伤的影响.方法 清洁级雄性SD大鼠18只,体重250～350 g,随机分为3组(n=6),假手术组(S组);肺移植组(L组)肺移植后恢复再灌注,冷缺血时间约1 h;L-NIL组再灌注即刻经尾静脉输注L-NIL 3 mg/kg.各组均于再灌注即刻经尾静脉注射0.5%伊文氏蓝0.2 ml.再灌注2 h时取左肺组织,测定肺湿/干重(W/D)比、伊文氏蓝含量、MDA含量、髓过氧化物酶(MPO)、诱导型一氧化氮合酶(iNOS)及内皮源性一氧化氮合酶(eNOS)活性;并行病理学观察.结果 与S组比较,L组肺组织W/D比和伊文氏蓝含量增加,MDA含量、MPO及iNOS活性升高,eNOS活性降低(P＜0.05).与L组比较,L-NIL组肺组织W/D比和伊文氏蓝含量减少,MDA含量、MPO及iNOS活性降低,eNOS活性升高(P＜0.05),肺组织毛细血管内充血减少,炎性细胞浸润减少.结论 再灌注早期静脉注射L-NIL可减轻大鼠移植肺缺血再灌注损伤.     

七氟醚预处理对大鼠肺缺血再灌注时肺组织血管紧张素转化酶mRNA表达的影响

目的 探讨七氟醚预处理对大鼠肺缺血再灌注时肺组织血管紧张素转化酶(ACE) mRNA表达的影响.方法 成年雄性SD大鼠54只,体重250 ～ 320 g,采用随机数字表法,将其分为3组(n=18):假手术组(S组)仅游离左肺门,但不阻断;肺缺血再灌注组(I/R组)采用阻断左肺门45 min后再灌注120 min的方法制备大鼠肺缺血再灌注模型;七氟醚预处理组(SP组)吸入2.1％七氟醚30min,停止吸入后10 min时后制备肺缺血再灌注模型.于再灌注30、60和120 min时随机取6只大鼠,处死取肺组织,测定湿/干重比(W/D比),采用比色法测定髓过氧化物酶(MPO)活性,采用RT-PCR法测定ACE mRNA的表达,光镜下观察肺组织病理学结果.结果 与S组比较,I/R组和SP组再灌注各时点肺组织W/D比、MPO活性和ACE mRNA表达水平均升高(P＜0.05);与I/R组比较,SP组再灌注各时点肺组织W/D比、MPO活性和ACE mRNA表达水平降低(P＜0.05).SP组肺组织病理学损伤较I/R组减轻.结论 七氟醚预处理可能通过下调ACE mRNA的表达从而减轻大鼠肺缺血再灌注损伤.     

雷帕霉素预处理对大鼠肢体缺血-再灌注诱发肺损伤的影响

目的探讨雷帕霉素预处理对大鼠肢体缺血-再灌注诱发肺损伤的影响及相关机制。方法健康雄性SD大鼠60只,4~5月龄,体重250~300g,采用随机数字表法分为五组:假手术组(S组)、肢体缺血-再灌注组(IR组)、雷帕霉素1、5、10mg/kg预处理组(R1、R5和R10组),每组12只。采用肢体缺血2h再灌注3h的方法制备肢体缺血-再灌注损伤模型。检测各组血清超氧化物歧化酶(SOD)活性、丙二醛(MDA)、IL-1β、IL-6和TNF-α的浓度;取肺组织,光镜下观察肺组织病理学结果,并测定肺组织湿干比重(W/D)。结果 IR、R1和R5组SOD活性明显低于S组(P0.05);R1、R5和R10组SOD活性明显高于IR组,且R5和R10组明显高于R1组,R10组明显高于R5组(P0.05)。IR、R1和R5组血清MDA、IL-1β、IL-6、TNF-α浓度和肺W/D明显升高(P0.05);R1、R5和R10组血清MDA、IL-1β、IL-6、TNF-α浓度和肺W/D明显降低,且R5和R10组明显低于R1组,R10组明显低于R5组(P0.05)。与S组比较,IR组肺组织病理学损伤加重;与IR组比较,R1、R5和R10组肺组织病理学损伤逐渐减轻。结论雷帕霉素预处理可减轻大鼠肢体缺血-再灌注诱发的肺损伤,并且呈剂量依赖性,剂量越大,其减轻肢体缺血-再灌注诱发肺损伤的作用越强,其机制可能与抗氧化应激和抗炎反应有关。     

肢体缺血预处理对兔肺缺血再灌注损伤的影响

目的 探讨肢体缺血预处理对兔肺缺血再灌注损伤的影响.方法 健康日本大耳白兔18只,体重2.0～2.5 kg,雌雄不拘,随机分为3组(n=6):假手术组(S组)开胸后左侧肺门穿线但不结扎,旷置观察340 min;缺血再灌注组(IR组)开胸旷置100 min,阻断左侧肺门,左肺不张后60 min再灌注180 min;肢体缺血预处理组(L组)捆绑双后肢10 min,松开10 min,反复3次后恢复灌注,60 min后阻断左侧肺门60 min,再灌注180 min.于缺血前、再灌注15、30、60、120、180 min时采集左颈内动脉血样行血气分析,计算呼吸指数(R1);于再灌注180 min时处死动物,取左肺上叶组织,测定超氧化物歧化酶(SOD)、髓过氧化物酶(MPO)活性及丙二醛(MDA)含量,计算肺湿干重比(W/D);取左肺下叶行支气管肺泡灌洗,计算肺通透性指数;取左肺中叶组织,观察肺组织病理学,进行弥漫性肺泡损伤(DAD)评分.结果 与s组比较,IR组RI、MDA含量、MPO活性、肺W/D、肺通透性指数和DAD评分升高,SOD活性降低(P<0.05或0.01);与IR组比较,L组RI,MDA含量、MPO活性、肺W/D、肺通透性指数和DAD评分降低,SOD活性升高(P<0.05或0.01);L组和S组间上述指标比较差异无统计学意义(P>0.05).L组和S组肺组织病理损伤程度较IR组减轻.结论 肢体缺血预处理可减轻兔肺缺血再灌注损伤.     

肢体缺血预处理对兔肺缺血再灌注损伤的影响

目的 探讨肢体缺血预处理对兔肺缺血再灌注损伤的影响.方法 健康日本大耳白兔18只,体重2.0～2.5 kg,雌雄不拘,随机分为3组(n=6):假手术组(S组)开胸后左侧肺门穿线但不结扎,旷置观察340 min;缺血再灌注组(IR组)开胸旷置100 min,阻断左侧肺门,左肺不张后60 min再灌注180 min;肢体缺血预处理组(L组)捆绑双后肢10 min,松开10 min,反复3次后恢复灌注,60 min后阻断左侧肺门60 min,再灌注180 min.于缺血前、再灌注15、30、60、120、180 min时采集左颈内动脉血样行血气分析,计算呼吸指数(R1);于再灌注180 min时处死动物,取左肺上叶组织,测定超氧化物歧化酶(SOD)、髓过氧化物酶(MPO)活性及丙二醛(MDA)含量,计算肺湿干重比(W/D);取左肺下叶行支气管肺泡灌洗,计算肺通透性指数;取左肺中叶组织,观察肺组织病理学,进行弥漫性肺泡损伤(DAD)评分.结果 与s组比较,IR组RI、MDA含量、MPO活性、肺W/D、肺通透性指数和DAD评分升高,SOD活性降低(P<0.05或0.01);与IR组比较,L组RI,MDA含量、MPO活性、肺W/D、肺通透性指数和DAD评分降低,SOD活性升高(P<0.05或0.01);L组和S组间上述指标比较差异无统计学意义(P>0.05).L组和S组肺组织病理损伤程度较IR组减轻.结论 肢体缺血预处理可减轻兔肺缺血再灌注损伤.     

肢体缺血预处理对兔肺缺血再灌注损伤的影响

目的 探讨肢体缺血预处理对兔肺缺血再灌注损伤的影响.方法 健康日本大耳白兔18只,体重2.0～2.5 kg,雌雄不拘,随机分为3组(n=6):假手术组(S组)开胸后左侧肺门穿线但不结扎,旷置观察340 min;缺血再灌注组(IR组)开胸旷置100 min,阻断左侧肺门,左肺不张后60 min再灌注180 min;肢体缺血预处理组(L组)捆绑双后肢10 min,松开10 min,反复3次后恢复灌注,60 min后阻断左侧肺门60 min,再灌注180 min.于缺血前、再灌注15、30、60、120、180 min时采集左颈内动脉血样行血气分析,计算呼吸指数(R1);于再灌注180 min时处死动物,取左肺上叶组织,测定超氧化物歧化酶(SOD)、髓过氧化物酶(MPO)活性及丙二醛(MDA)含量,计算肺湿干重比(W/D);取左肺下叶行支气管肺泡灌洗,计算肺通透性指数;取左肺中叶组织,观察肺组织病理学,进行弥漫性肺泡损伤(DAD)评分.结果 与s组比较,IR组RI、MDA含量、MPO活性、肺W/D、肺通透性指数和DAD评分升高,SOD活性降低(P<0.05或0.01);与IR组比较,L组RI,MDA含量、MPO活性、肺W/D、肺通透性指数和DAD评分降低,SOD活性升高(P<0.05或0.01);L组和S组间上述指标比较差异无统计学意义(P>0.05).L组和S组肺组织病理损伤程度较IR组减轻.结论 肢体缺血预处理可减轻兔肺缺血再灌注损伤.     

辛伐他汀预处理对肢体缺血再灌注诱发肺损伤大鼠肺组织血红素加氧酶-1表达的影响

目的 评价辛伐他汀预处理对肢体缺血再灌注诱发肺损伤大鼠肺组织血红素加氧酶-1(HO-1)表达的影响.方法 成年雄性SD大鼠48只,体重250～300 g,采用随机数字表法,将大鼠随机分为6组(n=8):假手术组(S组)、肢体缺血再灌注组(IR组)、辛伐他汀1、5、10 mg/kg组(S1组、S2组、S3组)和辛伐他汀对照组(SC组).采用夹闭股动脉2 h,再灌注3 h的方法制备肢体缺血再灌注模型.S组:仅分离股动脉和股静脉,不夹闭;IR组:制备肢体缺血再灌注模型;S1组、S2组、S3组:分别将辛伐他汀1、5、10 mg/kg溶于1 ml蒸馏水,于每13清晨灌胃1次,连续灌胃3 d后制备肢体缺血再灌注模型;SC组:辛伐他汀10 mg/kg溶于1 ml蒸馏水,于每日清晨灌胃1次,连续灌胃3 d.再灌注3 h时取颈动脉血样,行血气分析,记录PaO2和PaCO2,随后处死大鼠,取肺组织,观察病理学结果,计算湿重/干重比(W/D比),测定SOD活性,计数PMN,测定HO-1 mRNA及其蛋白的表达水平.结果 与S组比较,IR组PaO2及PaCO2降低,IR组、S1组和S2组肺组织W/D比和PMN计数升高,SOD活性降低(P＜0.05),S3组和SC组上述指标差异无统计学意义(P＞0.05),IR组、S1组、S2组、S3组和SC 组肺组织H0-1 mRNA及其蛋白表达上调(P＜0.01);与IR组比较,S1组、S2组和S3组PaO2、PaCO2及肺组织SOD活性升高,肺组织W/D比和PMN计数降低,肺组织HO-1 mRNA及其蛋白表达上调(P＜0.05或0.01);S1组、S2组和S3组肺组织WID比和PMN计数依次降低,SOD活性依次升高,HO-1 mRNA及其蛋白表达依次上调(P＜0.05或0.01).S1组、S2组和S3组肺组织病理性损伤较IR组减轻.结论 辛伐他汀预处理可上调肢体缺血再灌注大鼠肺组织HO-1的表达,从而产生肺保护作用,且呈剂量依赖性.

Abstract：

Objective To investigate the effects of simvastatin preconditioning on the pulmonary heme oxygenase-1 (HO-1) expression in rats with lung injury induced by ischemia-reperfusion (I/R) of hind limbs. Methods Forty-eight adult male SD rats weighing 250-300 g were randomly divided into 6 groups ( n = 8 each) : sham operation group (group S) ; I/R group; I/R + simvastatin 1,5, 10 mg/kg groups (S1 , S2, S3 groups) ; simvastatin control group (group SC) . I/R of hind limbs was produced by occlusion of bilateral femoral arteries for 2 h followed by 3 h reperfusion. Croups S1 , S2 , S3 received simvastatin 1, 5, 10 mg/kg respectively via an oro-gastric tube for 3 days before I/R. Group SC received simvastatin 10 mg/kg via an oro-gastric tube for 3 days. Arterial blood samples were taken at 3 h of reperfusion for blood gas analysis and PaO2 and PaCO2 were recorded. The animals were then sacrificed and the lungs removed immediately for pathologic examination and determination of the wet/dry lung weight ratio (W/D ratio), superoxide dismutase (SOD) activity and polymorphonuclear neutrophil (PMN) count . Hie expression of HO-1 mRNA and protein in lung tissues was detected using RT-PCR and Western blot analysis respectively.Results Alveolar edema, localized pulmonary atelectasis and large amount of PMN infiltration were found in I/R group and were ameliorated in S1, S2, S3 groups. Compared with group S, PaO2 and PaCO2 were significantly decreased in I/R group, W/D ratio and PMN count were increased and SOD activity was significantly decreased in I/R, S1 , S2 groups, and expression of HO-1 mRNA and protein was up-regulated in the other five groups ( P ＜ 0.05). PaO2, PaCO2 and SOD activity were significantly increased, W/D ratio and PMN count were significantly decreased, and HO-1 mRNA and protein expression was up-regulated in S1, S2 and S3 groups as compared with I/R group ( P ＜ 0.05 or 0.01). W/D ratio and PMN count were gradually decreased, SOD activity was gradually increased, and HO-1 mRNA and protein expression was gradually up-regulated in S1, S2 and S3 groups. Conclusion Simvastatin preconditioning has protective effect against lung injury induced by I/R of hind limbs in rats through up-regulation of HO-1 expression in the lung tissues and in a dose-dependent manner.     

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.     

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.     

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.     

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.     

The analgesic effect of racemic ketamine in patients with chronic ischemic pain due to lower extremity arteriosclerosis obliterans

Background : Ketamine in sub-dissociative doses has been shown to have analgesic and phantom-Limb pain, where conventional treatment has often failed. Chronic ischemic pain due to lower extremity arteriosclerosis obliterans often responds poorly to analgesics, and the pain-generating mechanisms are not well understood.
Methods : Eight patients with rest pain in the lower extremity due to arteriosclerosis obliterans were given sub-dissociative doses of 0.15, 0.30, or 0.45 mg/kg racemic ketamine and morphine 10 mg as a 5-min infusion on four separate days in a cross-over, double-blind, randomised protocol. Plasma levels of (S)- and (R)-ketamine and their nor-metabolites were analysed with an enantioselective high-performance liquid chromatography (HPLC) method. Pain levels were evaluated with a visual analogue scale (VAS).
Results : Individual pain levels were highly variable during and after all the infusions but the pooled pain levels showed a dose-dependent analgesic effect of ketamine with a transient but complete pain relief in all patients at the highest dose (0.45 mg/ kg). Side-effects, mainly disturbed cognition and perception, were pronounced and dose-dependent. Morphine 10 mg had an analgesic peak at 20 min and 5/8 patients had complete pain relief. The remaining 3 patients also had high baseline pain scores, indicating a higher analgesic potency for the 0.30 and 0.45 mg/ kg ketamine doses than for morphine 10 mg.
Conclusion : We have demonstrated a potent dose-dependent analgesic effect of racemic ketamine in clinical ischemic pain. Due to a narrow therapeutic window, this analgesic effect is probably best utilised in combination with other analgesics.     

Intravenous endotoxin does not increase tissue extravasation of albumin in rats

Background : It is unclear whether activation of the inducible nitric oxide synthase (iNOS) increases or decreases the extravasation of plasma.
Methods : Chloralose anaesthetised male Wistar rats received E. coli lipopolysacharide (LPS), 3 mg kg^-1 i.v., or the corresponding volume of saline, 3 or 5 h before the end of the experiment. Mean arterial pressure (MAP) and heart rate (HR) were recorded. Tissue clearance of radio-labelled albumin, during the last 2 h of each experiment, was determined by a double-isotope method. In separate animals, the serum concentration of nitrite and nitrate was determined, 5 h after LPS or the solvent.
Main Results : LPS initially decreased MAP and lastingly increased HR. In the 3-h LPS animals (n=8), tissue plasma clearance was lower in the heart and calf muscle and increased only in diaphragm, compared to corresponding control animals (n=8). In the 5-h LPS rats, clearance was lowered (n=8) in the entire gastrointestinal tract and in testes, compared to controls (n=8). The serum nitrite/nitrate concentration was higher in animals given LPS (n=6) than in controls (n=6).
Conclusion : After LPS, tissue clearance of albumin was not increased in any major tissue, in spite of increased serum levels of NO end products. Apparently, after activation of iNOS, the augmented release of NO is not necessarily associated with increased albumin extravasation.