食管鳞癌与细胞因子信号转导负调控因子3及其DNA甲基化的关系

目的 检测食管鳞癌(ESCC)组织中细胞因子信号转导负调控因子3(SOCS3)的DNA甲基化、mRNA及蛋白表达水平,探讨其在食管鳞癌发生、发展、浸润和转移中的作用.方法 采用甲基化特异性聚合酶链反应(MSP)、Real-Time聚合酶链反应(PCR)和Western blot法分别检测43例食管鳞癌组织中SOCS3的DNA甲基化、mRNA和蛋白表达水平,并与相应的癌旁正常食管组织进行对照研究,分析其与临床病理参数的关系.结果 (1)食管鳞癌组织SOCS3 DNA甲基化的阳性率(79.1%)明显高于癌旁组织(14.0%,P＜0.01);(2)食管鳞癌组织SOCS3 mRNA相对表达强度比值(0.53±0.30)明显低于癌旁组织(1.15±0.44,P＜0.01),食管鳞癌组织中甲基化组的SOCS3 mRNA表达(0.45±0.24)显著低于非甲基化组(0.86±0.29,P＜0.05);(3)食管鳞癌组织SOCS3蛋白表达(1.66±0.22)显著低于癌旁组织(1.83±0.15,P＜0.01),食管鳞癌组织中甲基化组SOCS3蛋白表达(1.61±0.21)显著低于非甲基化组(1.87±0.15,P＜0.01);(4)在TNM分期中Ⅲ期组表达均低于Ⅰ～Ⅱ期组(P＜0.05),伴有淋巴结转移组表达也都低于无淋巴结转移组(P＜0.05),未发现其在性别、年龄、家族史、吸烟史中有明显差异(P＞0.05);(5)食管鳞癌组织中SOCS3mRNA表达及其蛋白表达水平与肿瘤分化级别呈正相关(0.301＜r＜1,P＜0.05),与TNM分期、淋巴结转移呈负相关(-1＜r＜-0.301,P＜0.05).结论 食管鳞癌组织中SOCS3 DNA甲基化阳性率高,导致SOCS3基因表达下调,与食管鳞癌的分化、浸润和转移密切相关.     

miR-126在胃癌中的表达及其靶基因Crk的鉴定

目的:分析miR-126在胃癌中的表达水平并鉴定miR-126的靶基因,以阐明miR-126在胃癌发生机制中的功能。方法:采用qRT-PCR分别检测miR-126在胃癌细胞株、正常胃黏膜组织、永生化胃黏膜上皮细胞、胃癌及配对癌旁组织的表达水平,并与胃癌组织的临床病理指标进行相关性分析。采用生物信息学方法预测出miR-126的靶基因,并通过荧光素酶报告系统加以验证;采用qRT-PCR及Western印迹法检测miR-126对靶基因mRNA及蛋白质表达水平的影响。结果:qRT-PCR检测结果显示,miR-126在胃癌细胞株中的表达水平明显低于其在正常胃黏膜组织及永生化胃黏膜上皮细胞株的表达水平。miR-126在60例病人的胃癌组织中表达的水平显著低于其在配对癌旁组织中表达的水平;且胃癌组织miR-126表达水平低者,肿瘤组织体积较大,胃壁浸润较深,易发生淋巴结转移,病理分期也较晚。生物信息学分析提示Crk mRNA的3′UTR含有miR-126直接作用的靶序列,荧光素酶报告系统检测进一步验证了该靶序列,qRT-PCR及Western印迹法证实miR-126对Crk蛋白表达的调控发生在转录后水平。结论:miR-126有望成为研究胃癌的新型标志物;miR-126通过对其靶基因Crk的调控参与了胃癌的发生、发展过程。     

miR-126对内皮祖细胞增殖和迁移的影响以及靶基因的检测

目的 研究miR-126(micro RNA-126)对大鼠骨髓源性内皮祖细胞(endothelial progenitor cells,EPCs)增殖和迁移能力的影响,并探讨miR-126新的靶基因.方法 采用电转的方法,在EPCs中转染对照寡核苷酸和miR-126的模拟物或抑制物.噻唑蓝(MTT)法检测细胞增殖,划痕和transwell实验检测细胞迁移能力的改变.microRNA靶基因预测软件TargentScan在线分析miR-126的靶基因,并进一步用Western blot检测靶基因的表达变化.结果 (1) miR-126模拟物在转染后24 h对EPCs的增殖有促进作用(P＜0.01),转染后48和72 h,miR-126对EPCs增殖没有影响.(2)划痕和transwell实验证实miR-126模拟物可以促进EPCs的迁移(P＜0.01),miR-126抑制物抑制EPCs的迁移(P＜0.01).(3)TargetScan在线软件预测KANK2是miR-126的靶基因.(4) Western blot检测结果显示miR-126模拟物抑制KANK2的表达,miR-126抑制物促进KANK2的表达.结论 miR-126对EPCs的增殖有一过性的促进作用,miR-126可以促进EPCs的迁移能力并靶向KANK2蛋白,抑制KANK2蛋白的表达.     

黏蛋白1在食管鳞癌上皮细胞-间质细胞转化过程中的作用

目的 观察黏蛋白1(MUC1)对食管鳞癌细胞生物学行为的影响并探讨其在上皮细胞-间质细胞转化过程中的作用.方法 设计构建靶向MUC1基因的短发卡RNA(shRNA)慢病毒载体pGC-LV-MUC1小干扰RNA(siRNA)并感染人食管癌细胞株Eca109,检测其对MUC1表达的抑制作用;应用噻唑蓝(MTT)与Transwell侵袭实验检测抑制MUC1对肿瘤细胞增殖、侵袭能力的影响,并采用实时定量逆转录聚合酶链反应(RT-qPCR)与Western blot检测E-钙黏蛋白(E-cadherin)在各组细胞中的表达差异.结果 与对照组比较,感染pGC-LV-MUC1 siRNA后,Eca109细胞内MUC1基因水平(1.000±0.061比0.612±0.019)和蛋白水平(11.230±1.120比7.440±0.970)明显降低(P＜0.05);感染pGC-LV-MUC1 siRNA能显著抑制Eca109细胞的增殖活性,48 h (0.393±0.028比0.281 ±0.020),72 h(0.792±0.052比0.463 ±0.028,P＜ 0.05);感染pGC-LV-MUC1 siRNA后,Eca109细胞的侵袭数量也明显降低[(87±4)个比(48±7)个,P＜0.05];而Eca109细胞内E-cadherin基因水平(1.000±0.072比2.510±0.767)和蛋白水平(0.070±0.020比0.130±0.030)明显增高(P＜0.05).结论 MUC1可能通过诱导上皮细胞-间质细胞转化(EMT)而促进食管鳞癌细胞增殖、侵袭.     

转录因子Snail介导E-cadherin表达在食管鳞癌迁移和侵袭中的作用

目的探索转录因子Snail、E-cadherin基因在食管鳞癌中的表达及临床病理意义,明确其对食管鳞癌迁移和侵袭的影响。方法食管鳞癌组织及对应癌旁组织标本30例,PCR检测Snail、E-cadherin表达;以癌/癌旁组织相对表达量表示Snail及E-cadherin在mRNA水平表达的差异,分析其与临床病理特征间关系;随机抽取其中4例,Western blot检测Snail、E-cadherin表达。筛选三株食管鳞癌细胞株中的一株进行转染,利用Snail小干扰RNA作为实验组,以双链无义RNA转染作为对照组,检测Snail和E-cadherin表达水平变化,行细胞划痕、侵袭实验。结果 30例食管鳞癌组织较癌旁组织中Snail相对表达量高(1.96±0.75/0.52±0.43,P=0.04),E-cadherin相对表达量低(0.66±0.31/2.19±0.62,P=0.02);食管鳞癌中Snail相对高表达、E-cadherin相对低表达程度均与癌组织浸润深度(P=0.009)、淋巴结转移与否(P=0.047)相关。其中4例病人,癌组织相比对应癌旁组织中Snail蛋白表达高(0.73±0.13/0.23±0.08,P=0.00),而E-cadherin蛋白表达低(0.10±0.06/0.60±0.14,P=0.00)。选取EC109为实验细胞株,PCR结果显示,Snail小干扰RNA转染组较对照组中Snail表达减少(0.53±0.05/1.00±0.15,P=0.00),同时,E-cadherin表达上调(3.28±0.26/1.00±0.18,P=0.00);Western blot检测显示,抑制Snail蛋白表达后(0.25±0.05/0.41±0.10,P=0.03)EC109中E-cadherin蛋白表达上调(0.83±0.11/0.29±0.05,P=0.02)。划痕实验及Transwell细胞侵袭实验示,下调Snail表达后EC109迁移、侵袭能力均减弱(P0.05)。结论转录因子Snail在食管鳞癌中相对高表达,并可能通过介导E-cadherin表达影响肿瘤迁移与侵袭。     

食管鳞癌RASSF1A基因启动子区甲基化研究

目的 研究肿瘤抑制基因RASSF1A启动子区甲基化所致该基因表达抑制在我国食管鳞癌发生中的作用及可能机制. 方法 用甲基化特异PCR技术(MSP)检测43例原发性食管鳞癌标本及6例对照食管上皮组织标本、食管鳞癌细胞系TE11和TE12中RASSF1A启动子甲基化状态;逆转录(RT)-PCR法检测5-氮-2′-脱氧胞苷(5-Aza-CdR)处理前后食管鳞癌细胞系中RASSF1A mRNA表达水平;Western blot方法检测食管鳞癌细胞系中细胞微管蛋白的表达. 结果 20.9%(9/43)原发性食管鳞癌标本有RASSF1A启动子超甲基化,正常食管上皮组织未发现该基因超甲基化改变.RASSF1A基因甲基化与食管癌患者的性别和TNM分期无关(P＞0.05),但在不同年龄组间的差异有统计学意义(P＜0.05).TE12细胞RASSF1A启动子发生甲基化,RT-PCR检测不到RASSF1A mRNA.TE11细胞系启动子未发生甲基化,RT-PCR检测其有RASSF1A mRNA表达.5-Aza-CdR处理可使TE12重新表达RASSF1A mRNA.TE12细胞的β-微管蛋白水平比TE11细胞低87.8%. 结论 原发性食管鳞癌存在RASSF1A启动子超甲基化,该基因甲基化与年龄相关.RASSF1A在食管鳞癌细胞系表达抑制与其甲基化状态有关.RASSF1A表达缺失可能导致β-微管蛋白减少.     

微小RNA-29b/c与髓样细胞白血病-1在胃癌中的相互作用关系

目的 探讨胃癌细胞中微小RNA-29b和微小RNA-29c (miR-29b/c)与髓样细胞白血病-1(Mcl-1)的相互作用关系.方法 实时定量聚合酶链反应(Real-time PCR)和Western blot检测高表达miR-29b/c后胃癌细胞中Mcl-1 mRNA和蛋白表达水平,载体构建及荧光素酶报告基因验证两者之间的作用关系,4',6-二脒基-2-苯基吲哚(DAPI)染色技术验证miR-29b/c后对胃癌细胞凋亡的作用.结果 高表达miR-29b/c能够显著下调Mcl-1 mRNA在胃癌细胞中的表达量(0.860±0.006比0.513±0.061,P＜0.05及0.860±0.006比0.512±0.104,P＜0.01)并下调Mcl-1蛋白表达水平.Mcl-1是miR-29b/c的靶基因(1 234 000±42 720比54 900±13 700,P＜0.01及652 700±14 010比283 100±12 750,P＜0.01).高表达miR-29b/c能够显著增加胃癌细胞的凋亡率[(1.961±0.476)％比(6.319±1.725)％,P ＜0.05及(1.961±0.476)％比(4.878±0.614)％,P＜0.01].结论 miR-29b/c通过调控Mcl-1在胃癌细胞中的表达可能是胃癌发病机制之一.     

微小RNA-181b及其靶基因肝癌缺失基因-1在肝癌发生中的作用

目的 探讨微小RNA(miRNA,miR)-181b对肝癌缺失基因-1(DLC-1)的调控及其在肝癌发病中的作用.方法 通过实时荧光定量聚合酶链反应(FQ-PCR)和Western blot检测4份正常肝脏组织,17份癌旁组织、肝癌组织及肝癌SMMC7721细胞、胚肝LO2细胞中miR-181b和DLC-1的mRNA和蛋白质表达水平.应用miR-181b抑制剂下调肝癌细胞SMMC7721中miR-181b表达后,实时定量聚合酶链反应和Westem blot检测SMMC7721细胞中DLC-1表达水平的变化.结果 miR-181b在正常肝组织、癌旁组织和肝癌组织中的相对表达量分别为0.162 ±0.004、0.175±0.021和0.656±0.034,肝癌组织高于正常肝组织(P＜0.05).miR-181b在SMMC7721细胞中的表达较LO2细胞上调(0.723±0.042和0.262±0.037,P＜0.01).DLC-1 mRNA在正常肝组织、癌旁组织和肝癌组织中的相对表达量分别为0.392±0.094、0.187 ±0.043和0.081 ±0.012,肝癌组织低于正常肝组织(P＜0.05);DLC-1蛋白在正常肝组织、癌旁组织和肝癌组织中的相对表达量分别为0.423±0.026、0.214±0.029和0.112±0.021,差异有统计学意义(P＜0.01).miR-181b抑制剂转染SMMC7721细胞后,DLC-1蛋白在空白组、转染组和阴性对照组的相对表达量分别为0.132±0.027、0.379±0.019和0.125±0.015,转染组较其他两组明显升高(P＜0.05).结论 miR-181b在肝癌组织中表达上调,其抑制DLC-1的表达可能是肝癌发生的重要机制.     

乳腺癌抗雌激素药物耐药蛋白1在食管鳞癌血清和组织中的表达及临床意义

目的 探讨乳腺癌抗雌激素药物耐药蛋白1( BCAR1)在食管鳞癌血清和组织中的表达及临床意义.方法 采用酶联免疫吸附试验(ELISA)检测2010年2月至2011年1月间46例食管鳞癌患者和25例正常人血清BCAR1水平;应用组织芯片和免疫组织化学方法检测2004年2月至2006年7月间106例食管鳞癌和癌旁正常组织中BCAR1表达.结果 食管鳞癌组BCAR1血清水平显著高于正常对照组(P＜0.01);晚期食管鳞癌BCAR1血清水平显著高于早期食管鳞癌组和正常对照组(P＜0.01);切除肿瘤后,血清BCAR1水平有逐渐下降趋势.BCAR1蛋白在食管鳞癌组织中阳性率为97％( 103/106),癌旁正常食管组织中有16例弱阳性,阳性率为15％ (16/106),两者差异有统计学意义(P＜0.01);BCAR1阳性表达与食管鳞癌的分化明显相关(P＜0.05),与年龄、性别、淋巴结转移、浸润深度和TNM分期明显无关(P＞0.05).生存分析提示BCAR1高表达组生存时间少于低表达组(P＜0.01);经COX模型多因素生存分析,显示BCAR1表达和淋巴结转移为独立预后因素.结论 食管鳞癌血清和组织中BCAR1水平显著高于正常对照组,并与疾病进展、治疗效果、分化程度和预后相关,可作为食管鳞癌诊断和判断预后重要新的肿瘤分子标记.     

长链非编码RNA牛磺酸上调基因靶向作用于微小RNA-145对甲状腺癌细胞侵袭的影响及其机制

目的观察甲状腺乳头状癌(PTC)细胞中长链非编码RNA(lncRNA)牛磺酸上调基因(TUG1)靶向作用于微小RNA(microRNA,miR)-145/锌指E-盒结合同源异形盒-1(ZEB1)对细胞侵袭能力的影响。方法实验标本选自2018年4月至2019年12月间河北医科大学第二医院甲状腺乳腺外科收集的甲状腺乳头状癌及癌旁标本共30例,采用实时荧光定量聚合酶链反应(polymerase chain reaction,PCR)的方法观察乳头状甲状腺癌及其癌旁组织中lncRNA TUG1及miR-145的表达水平;将lncRNA TUG1 shRNA和miR-145 mimics分别转染到甲状腺乳头状癌TPC-1细胞中,利用Transwell细胞侵袭实验观察lncRNA TUG1和miR-145对甲状腺癌细胞侵袭能力的影响。应用生物信息学及双荧光素酶报告基因分析lncRNA TUG1和miR-145的关系及miR-145的靶基因。同时,利用蛋白质印迹法(Western blot)实验检测lncRNA TUG1和miR-145对靶蛋白表达水平的影响。两组间统计学差异通过双尾t检验进行分析。结果实时荧光定量PCR实验结果显示,lncRNA TUG1在甲状腺乳头状癌组织中的表达水平(4.43±0.07)高于癌旁组织(1.13±0.06),差异有统计学意义(t=3.124,P<0.05),miR-145的表达水平(0.39±0.08)低于癌旁组织(1.08±0.04),差异有统计学意义(t=2.937,P<0.05);甲状腺乳头状癌TPC-1细胞中转染lncRNA TUG1 shRNA组及miR-145 mimics组侵袭细胞数[(292.4±48.2)、(234.2±42.4)个]低于各自对照组侵袭细胞数[(452.9±50.8)、(439.4±39.8)个],差异有统计学意义(t=3.205,P<0.05;t=3.186,P<0.05);生物信息学及双荧光素酶报告基因分析结果显示,lncRNA TUG1可以与miR-145互补结合,ZEB1是miR-145的靶基因;lncRNA TUG1 shRNA组细胞ZEB1蛋白表达水平(0.33±0.12)低于lncRNA对照组细胞中ZEB1蛋白表达水平(1.17±0.12),差异有统计学意义(t=3.320,P<0.05),miR-145 mimics转染组细胞蛋白表达水平(0.46±0.11)低于miRNA对照组细胞中ZEB1蛋白表达水平(1.05±0.12),差异有统计学意义(t=3.450,P<0.05)。结论lncRNA TUG1能够靶向作用于miR-145/ZEB1调控甲状腺癌细胞的侵袭能力。     

Vasopressor hormone response following mesenteric traction during major abdominal surgery

Background : We investigated the vasopressor hormone response following mesenteric traction (MT) with hypotension due to prostacyclin (PGI₂) release in patients undergoing abdominal surgery with a combined general and epidural anesthesia. Methods : In a prospective, randomized, placebo-controlled study we administered 400 mg ibuprofen (i.v.) in 42 patients scheduled for abdominal surgery. General anesthesia was combined with epidural anesthesia (T4-L1). Before as well as 5, 15, 30, 45, and 90 min after MT we recorded plasma osmolality, hemodynamics and measured 6-keto-PGFlα (stabile metabolite of PGI₂), TXB₂ (stabile metabolite of thromboxane A₂) active renin, and arginine vasopressin (AVP) plasma concentrations by radioimmunoassay. Catecholamine levels were assessed by high-pressure liquid chromatography (HPLC) with electrochemical detection. Results : Following MT, arterial hypotension occurred along with a substantial PGI₂ release. This was completely abolished by ibuprofen administration. Although plasma levels of 6-keto-PGF_1α (1133 (708) vs. 60 (3) ng/L, median (median absolute deviation), P=0.0001, placebo vs. ibuprofen) remained significantly elevated, blood pressure was restored within 30 min after MT in the placebo group. At the same point in time plasma concentrations of TXB² (164 (87) vs. 58 (1) ng/L, P=0.0001), epinephrine (46 (33) vs. 14 (6) ng/L, P=0.001), AVP (41 ± (18) vs. 12 (7) ng/L, P=0.0004), and active renin (27 (12) vs. 12 (4) ng/L, P = 0.001) were significantly higher in placebo-treated patients. Conclusion : Under combined general and epidural anesthesia arterial hypotension following MT due to endogenous PGI₂ release is associated with enhanced release of AVP, active renin, epinephrine and thromboxane A₂, presumably contributing to hemodynamic stability within 30 min after MT.     

A comparison of the inhibitory effects of four volatile anaesthetics on the metabolism of chlorzoxazone, a substrate for CYP2E1, in rabbits

Background: Halothane inhibits in vitro and in vivo activity of cytochrome P-450 (CYP) 2E1. There are several fluorinated volatile anaesthetics besides halothane, and most of them are defluorinated by CYP2E1. It is unclear whether other fluorinated anaesthetics inhibit the in vivo activity of CYP2E1.
Methods: We compared the inhibitory effects of therapeutic concentrations of four inhalational anaesthetics, halothane, enflurane, isoflurane, and sevoflurane, on chlorzoxazone metabolism in rabbits receiving artificial ventilation.
Results: All four inhalational anaesthetics decreased arterial blood pressure and increased plasma chlorzoxazone concentration. However, no significant differences in the plasma chlorzoxazone concentration were found between the four anaesthetics. The estimated chlorzoxazone clearance increased after beginning inhalation with all four agents, but no significant difference in clearance was noted between agents.
Conclusions: At therapeutic concentrations, the in vivo inhibitory effect on chlorzoxazone metabolism was similar for all four inhalational anaesthetics examined, even though their chemical characteristics and extent of hepatic metabolism differ considerably.     

A Teaspoon Pump for Pumping Blood with High Hydraulic Efficiency and Low Hemolysis Potential

Abstract: Virtually all blood pumps contain some kind of rubbing, sliding, closely moving machinery surfaces that are exposed to the blood being pumped. These valves, internal bearings, magnetic bearing position sensors, and shaft seals cause most of the problems with blood pumps. The original teaspoon pump design prevented the rubbing, sliding machinery surfaces from contacting the blood. However, the hydraulic efficiency was low because the blood was able to "slip around" the rotating impeller so that the blood itself never rotated fast enough to develop adequate pressure. An improved teaspoon blood pump has been designed and tested and has shown acceptable hydraulic performance and low hemolysis potential. The new pump uses a nonrotating "swinging" hose as the pump impeller. The fluid enters the pump through the center of the swinging hose; therefore, there can be no fluid slip between the revolving blood and the revolving impeller. The new pump uses an impeller that is comparable to a flexible garden hose. If the free end of the hose were swung around in a circle like half of a jump rope, the fluid inside the hose would rotate and develop pressure even though the hose impeller itself did not "rotate"; therefore, no rotating shaft seal or internal bearings are required.     

Microspheres Based Detoxification System: A New Method in Convective Blood Purification

Abstract: A variety of protein-bound or hydrophobic substances, accumulating as a result of pathologic conditions such as exogenous or endogenous intoxications, are removed poorly by conventional detoxification methods because of low accessibility (hemodialysis), insufficient adsorption capabilities (hemosorption), low efficiency (peritoneal dialysis), or economic limitations (high-volume plasmapheresis). Combining advantages of existing methods with microspheric technology, a module-based system was designed. Major operating parameters of the latter can be modified to allow for adjustment to individual clinical situations. An extracorporeal blood circuit including a plasmafilter is combined with a secondary high-velocity plasma circuit driven by a centrifugal pump. Different microspheric adsorbers can be combined in one circuit or applied in sequence. Thus, a prolonged treatment can be tailored using specially designed selective adsorber materials. Comparing this system with existing methods (high-flux hemodialysis, molecular adsorbent recycling system), results from our in vitro studies and animal experiments demonstrate the superior efficiency of substance removal.     

Tissue perfusion in relation to cardiac output during continuous positive-pressure ventilation and administration of propranolol or verapamil

Background : Our objective was to determine whether administration of propranolol or verapamil modifies the hemodynamic adaptation to continuous positive-pressure ventilation (CPPV), in particular the regional distribution of cardiac output (CO).
Methods : General hemodynamics and regional blood flows assessed by microsphere technique (15 (μm) were recorded in 16 anesthetized pigs during spontaneous breathing (SB) and CPPV with 8 cm H₂O end-expiratory pressure (CPPV8) before and after intravenous administration of propranolol (0.3 mg · kg⁻¹ followed by 0.15 mg · kg⁻¹ · h⁻¹, n=8) or verapamil (0.1 mg · kg⁻¹ followed by 0.3 mg · kg⁻¹ · h⁻¹, n=8).
Results : CPPV8 depressed CO by 25% without shifts in its relative distribution with the exception of a noteworthy increase in adrenal perfusion. Propranolol increased arterial blood pressure, and due to a fall in heart rate, CO dropped by 25%. The kidneys and, to a lesser extent, the splanchic region and central nervous system received increased fractions of the remaining CO at the expense of skeletal muscle flow. Similar patterns were seen during SB and CPPV8 such that the combination of propranolol and CPPV8 depressed CO by 50%. The circulatory effects of verapamil were less evident but myocardial perfusion tended to increase.
Conclusions : The combination of propranolol or verapamil with CPPV does not result in any specific hemodynamic interaction in anesthetized pigs, except that the combined effect of propranolol and CPPV may severely reduce CO.     

Volatile anaesthetics reduce adhesion of blood platelets under low-flow conditions in the coronary system of isolated guinea pig hearts

Background : Inhibitory effects of volatile anaesthetics on platelet aggregation have been demonstrated in several studies. However, the influence of volatile anaesthetics on intracoronary platelet adhesion has not been elucidated so far.
Methods : Isolated hearts of guinea pigs were perfused with buffer in the absence or presence of volatile anaesthetics (0.5 and 1 MAC) at constant coronary flow rates of 5 ml/min for 25 min, then 1 ml/min for 30 min and again 5 ml/min for 10 min. Before, during and after low-flow perfusion, a bolus of human platelets was applied into the coronary system. To simulate thrombogenic conditions, 0.3 U/ml human thrombin was infused during low-flow perfusion and reperfusion. The number of platelets sequestered to the endothelium was calculated from the difference between coronary in- and output of platelets. The myocardial production of lactate and consumption of pyruvate and coronary perfusion pressure were also determined.
Results : At a flow rate of 5 ml/min only about 3% of the applied platelets did not emerge from the coronary system, in any group. In contrast, 13.1±1.2% (mean±SEM) of infused platelets became adherent in low-flow perfusion in the control group without anaesthetic. The adherence was reduced with each 1 MAC isoflurane (to 6.2±1.2%), sevoflurane (to 4.4±0.9%) or halothane (to 3.2±1.5%) (each P <0.05 vs. control). Volatile anaesthetic, 0.5 MAC, did not inhibit platelet adhesion to a statistically significant extent in any case. Perfusion pressure and metabolic parameters were not statistically different between the control and the hearts exposed to anaesthetics.
Conclusion : Volatile anaesthetics in a concentration of 1 MAC can reduce the adhesion of platelets in the coronary system under reduced flow conditions. This action does not arise from vasodilation or inhibition of ischaemic stress.     

Bariatric Surgery in Some "Central and East-European (former Eastern bloc)"Countries - Current Status and Prediction for the Next Millennium

Background: Obesity is increasing globallly, including in the formerly "Eastern Bloc" countries. Methods: A survey was made of obesity and bariatric surgery. Results: In the 8 East and Central European countries studied, with total population 300 million, roughly 43% of the population was overweight (BMI 25-30), 23% obese (BMI > 30), with about 15 million people morbidly obese (BMI > 40). From 0-10 morbidly obese individuals/100,000/year undergo bariatric surgery. Conclusion: Most countries were found to provide inadequate treatment for obesity.The majority of the morbidly obese are not treated effectively. However, health-care awareness of obesity and bariatric surgeons are slowly increasing.     

Is the recovery profile of mivacurium independent of the rate of decay of its plasma concentration in patients with normal plasma cholinesterase activity?

Background: The duration of action of muscle relaxants is poorly correlated to the rate of decay of their plasma concentration. The plasma concentration of mivacurium may rapidly decrease below its active concentration because of the extensive hydrolysis of mivacurium. By inflating a tourniquet on one upper limb for 3 min after the administration of atracurium, mivacurium or vecuronium, we studied the influence of the initial decline of their plasma concentration on their effect. Methods: In 50 patients anaesthetised with thiopental, isoflurane and fentanyl, the effect of bolus doses of 0.15 or 0.25 mg . kg^?1 mivacurium (MIV 15, MIV 25), 0.3 or 0.5 mg . kg^?1 atracurium (ATR 30, ATR 50) and 0.06 or 0.1 mg . kg^?1 vecuronium (VEC 06, VEC 10) were measured on both arms (evoked response of the adductor pollicis to train-of-four stimulation every 12 s), a tourniquet being applied on one arm just before and during 3 min after the muscle relaxant bolus. Results: Tourniquet inflation of 3 min almost abolished the neuromuscular effect of mivacurium. In the vecuronium groups and in the ATR 50 group, tourniquet inflation did not modify the maximum degree of depression of the twitch response. Also, the duration of action of vecuronium was unaffected by the tourniquet. In the ATR 30 group, times to return of the twitch response to 25% (duration 25%) and 75% (duration 75%) of control response were significantly shorter in the cuffed arm, 23 min vs 27 min, and 41 min vs 45 min, respectively. In the ATR 50 group, only duration 25% was significantly shorter in the cuffed arm (41 min vs 45 min). Conclusion: The results suggest that the rate of decline of the plasma concentration of mivacurium is so rapid, that a very low and almost clinically ineffective concentration is present as soon as 3 min after its administration. The results also indicate that the recovery from a mivacurium-induced neuromuscular blockade is not influenced by the rate of decay of its plasma concentration in patients with genotypically normal plasma cholinesterase.     

Membranes in Artificial Organs

Abstract: Membrane processes play a pivotal and enabling role in modern replacement therapy for acute and chronic organ failure and in the management of immunologic diseases. In fact, virtually all contemporary extracorporeal blood purification methods employ membrane devices, and the next generation of artificial organs and tissue engineering therapies are almost certain to be similarly grounded in membrane technology. In this short essay, we comment on the similarities and differences among synthetic membranes and their natural counterparts and also provide a critical overview of the demographics and technology of hemodialysis, hemofiltration, apheresis, oxygenation, and emerging membrane technologies and applications.     

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.