自噬对肝卵圆细胞在缺血缺氧微环境中增殖的影响

目的观察自噬对肝卵圆细(hepatic oval cell,HOC)在缺血缺氧微环境中增殖的影响。方法体外培养肝卵圆细胞建立缺血缺氧模型,检测缺血缺氧0、2、4、8和24 h的自噬情况,每个时间点设置单纯缺血缺氧组(ischemia-hypoxia),缺血缺氧+氯喹组(ischemia-hypoxia+CQ),正常对照组(control)。以CCK-8法检测各组HOC增殖能力的变化;Hoechst 33258染色观察细胞凋亡;应用丹(磺)酰戊二胺(Monodansylcadaverine,MDC)染色荧光定位法、免疫荧光细胞化学染色法观察各组细胞的自噬,免疫印迹法(Western blotting)检测各组细胞LC3-II/I蛋白表达情况。结果缺血缺氧对肝卵圆细胞的增殖有抑制作用,且缺血缺氧时间越长抑制越明显。与对照组相比,随着缺血缺氧的时间的延长,MDC染色阳性细胞数,细胞免疫荧光强度和自噬特异标记分子LC3 II水平及LC3-II与LC3-I的比值显著增加(P0.05)。加入自噬抑制剂CQ后肝卵圆细胞在缺血缺氧微环境中的存活率与未加CQ比较显著下降(P0.05)。结论缺血缺氧可以抑制肝卵圆细胞增殖,并且可诱导肝卵圆细胞自噬;自噬有利于肝卵圆细胞在缺血缺氧微环境中稳定细胞内环境,维持细胞的存活。     

miR-21在TGF-β1引起的肝卵圆细胞上皮间质转化中的作用

[摘 要] 目的 探讨microRNA-21（miR-21）在TGF-β1引起的肝卵圆细胞（hepatic oval cell,HOC）上皮间质转化（epithelial mesenchymal transition,EMT）中的作用。方法 体外培养大鼠肝卵圆细胞,用10 ng/mL TGF-β1刺激HOC 1、3、5、7 d后,Western blotting检测EMT相关蛋白（E-cadherin、N-cadherin和Vi-mentin）表达情况;用10 ng/mL TGF-β1刺激HOC 5 d后,实时荧光定量PCR检测miR-21的表达情况;分别用miR-21增强和抑制慢病毒转染HOC构建稳定的细胞株,PCR检测miR-21的表达情况;接着用TGF-β1刺激miR-21抑制慢病毒转染的HOC 5 d,Western blotting检测E-cadherin、N-cadherin和Vimentin的表达;用miR-21增强慢病毒转染HOC后,Western blotting检测E-cadherin、N-cadherin和Vimentin的表达。结果 TGF-β1刺激HOC 1、3、5、7 d后,E-cadherin逐渐减低,N-cadherin和Vimentin逐渐升高。TGF-β1刺激HOC 5 d后miR-21的表达增强了4.32倍。分别用增强和抑制慢病毒转染HOC后,miR-21的表达增强了3.82倍和抑制了0.22倍。下调miR-21表达后,TGF-β1致HOC的EMT作用减弱。miR-21过表达后,HOC发生了EMT。结论 抑制miR-21的表达可以减少TGF-β1引起的HOC的EMT作用,从而减轻肝纤维化。     

circUTRN24通过肝星状细胞自噬介导胆道闭锁肝纤维化

目的 探究胆道闭锁中circUTRN24与自噬途径的关联,以及是否通过自噬参与胆道闭锁的肝纤维化过程。方法 通过RT-qPCR、Western blot分别检测BA组和对照组的肝组织中circUTRN24以及自噬相关蛋白的表达,并进行相关性分析。在细胞水平,通过慢病毒转染使人肝星状细胞系LX-2过表达circUTRN24,Western blot检测转染前后自噬相关蛋白Beclin-1、LC3以及HSC活化相关指标α-SMA、COL-Ⅰ的表达水平。结果 胆道闭锁患儿肝组织中circUTRN24以及自噬相关蛋白Beclin-1的表达明显高于对照组,并且呈正相关关系。过表达circUTRN24的LX-2细胞中自噬相关蛋白Beclin-1、LC3-Ⅱ及HSC活化相关指标α-SMA、COL-Ⅰ均明显升高。结论circUTRN24可能通过调控肝星状细胞自噬过程促进胆道闭锁肝纤维化的进展。     

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。     

MiR-506-3p与自噬相关因子在烧伤后皮肤成纤维细胞中的表达研究

目的：分析烧伤组织中miR-506-3p的表达及其对自噬水平的调控。方法：提取正常皮肤组织、烧伤皮肤组织和热处理成纤维细胞细胞的总RNA,采用荧光定量RT-qPCR、Western Blot分别检测各细胞miR-506-3p和自噬相关因子(LC3-Ⅱ/Ⅰ比值、Atg5、p62及CollagenⅠ)表达水平;采用同样方法检测miR-506-3p模拟物或miR-506-3p抑制剂转染到真皮成纤维细胞中对上述自噬相关因子表达水平的影响,并利用CCK-8方法检测转染细胞的增殖效率。结果：与正常组织相比,烧伤组织和热处理成纤维细胞中,miR-506-3p的表达下调,自噬相关因子LC3-Ⅱ/Ⅰ比值、Atg5及Collagen Ⅰ的表达显著上调(P<0.01),而p62表达下调(P<0.05);miR-506-3p抑制剂转染到皮肤成纤维细胞中,miR-506-3p表达显著降低,促进了细胞增殖和自噬发生,而miR-506-3p的过表达则显示出相反的作用(P<0.05)。结论：miR-506-3p在烧伤皮肤组织恢复中发挥着积极作用,对调节成纤维细胞的自噬水平具有重要作用,有可能成为烧伤...     

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。     

酸环境对大鼠髓核细胞自噬及功能的影响

目的:观察酸环境下髓核细胞(nucleus pulposus cells,NPCs)中卵巢癌G蛋白偶联受体1(ovarian cancer G-protein-coupled receptor 1,OGR1)和自噬相关蛋白LC3的表达水平,探讨自噬激活机制,初步分析其对细胞功能的影响。方法:取SD大鼠正常髓核组织,分离培养NPCs,甲苯胺蓝、阿利新染色和Ⅱ型胶原免疫荧光检测鉴定NPCs。扩增培养NPCs,取第2代NPCs,在pH值为6.2、6.4、6.8、7.0、7.2和7.4的培养基中培养24h,免疫荧光观察NPCs中OGR1的表达情况,Western blotting检查细胞中OGR1和LC3-Ⅱ蛋白表达水平;在pH值为6.4的培养基中培养0、3h、6h、12h、24h、48h后,采用Western blotting检测NPCs中LC3-Ⅰ和LC3-Ⅱ蛋白表达水平。构建3个不同靶点的OGR1干扰序列,检测最合适滴度慢病毒,用最适滴度慢病毒转染NPCs,使用Western blotting和Real-time PCR检测不同干扰序列的沉默效果,选取最适干扰系列构建OGR1-shRNA慢病毒载体。取第2代NPCs,分为4组:正常组(DMEM培养基)、pH值6.4培养基组(空白组)、pH值6.4培养基空载体组(空载体组)、pH值6.4培养基OGR1-shRNA慢病毒转染组(转染组),培养24h后用Western blotting检测LC3-Ⅱ和p62蛋白表达水平;Alcian染色观察NPCs中蛋白多糖的表达情况。结果:(1)分离培养的细胞高表达蛋白多糖和Ⅱ型胶原,符合NPCs表型。(2)OGR1蛋白表达水平与培养基pH值相关,pH值7.0时,OGR1和LC3-Ⅱ蛋白表达水平显著性升高(P0.05),pH值6.4时表达量最高。(3)在pH值6.4的培养基中培养时,细胞中LC3-Ⅰ和LC3-Ⅱ的表达量与培养时间有关,24h时达高峰,48h仍较高。(4)3个干扰序列对OGR1均有沉默作用,与对照组比较有显著性差异(P0.05),OGR1-shRNA1沉默效果最佳。(5)转染组细胞在pH值6.4的培养基中培养24h后,LC3-Ⅱ表达水平显著性低于空载体组(P0.05);p62表达水平显著性高于空载体组(P0.05);蛋白多糖的表达低于空载体组(P0.05)。结论:酸环境可促进大鼠NPCs中OGR1蛋白表达和自噬水平升高,OGR1介导了细胞自噬的激活,并影响NPCs的生物学功能。     

缺氧条件下大鼠髓核细胞中缺氧诱导因子1α与自噬相关分子的表达及相关性分析

目的探讨缺氧条件下大鼠髓核细胞中缺氧诱导因子1α(hypoxia inducible factor 1α,HIF-1α)与自噬相关分子Beclin1、LC3B的表达及其相关性。方法取健康成年SD大鼠髓核组织,分离培养髓核细胞并传代。取第3代髓核细胞行HE染色和Ⅱ型胶原酶免疫荧光染色鉴定后,随机分为4组。A组细胞于常氧条件下(37℃、5%CO2、20%O2)培养,B组细胞于缺氧条件下(37℃、5%CO2、1%O2)培养,C组细胞转染HIF-1α-小干扰RNA后于缺氧条件下培养,D组细胞加入自噬抑制剂3-MA后于缺氧条件下培养。各组细胞培养8 h后,采用Western blot和实时荧光定量PCR(real-time fluorescence quantitative PCR,qRT-PCR)检测HIF-1α与自噬相关分子Beclin1、LC3B的表达情况。结果经分离纯化的第3代大鼠髓核细胞HE染色后细胞质呈淡粉色,细胞核呈蓝黑色;Ⅱ型胶原酶免疫荧光染色为阳性。Western blot和qRT-PCR检测示,B组HIF-1α、Beclin1和LC3B蛋白及mRNA相对表达量均显著高于A组(P<0.05),C组均显著低于B组,差异均有统计学意义(P<0.05)。D组HIF-1α蛋白和mRNA相对表达量与B组比较差异无统计学意义(P>0.05),Beclin1和LC3B蛋白和mRNA相对表达量均较B组显著降低(P<0.05)。结论缺氧条件能诱导大鼠髓核细胞中HIF-1α和自噬相关分子Beclin1、LC3B的表达,且HIF-1α与自噬相关分子的表达具有相关性,即HIF-1α下调能降低自噬相关分子的表达,而缺氧条件下自噬水平下调对HIF-1α的表达无明显影响。     

诱导/封闭自噬相关基因7对肾癌786-0细胞自噬的调控作用研究

目的 探讨诱导/封闭Atg7对肾癌786-0细胞自噬的调控作用。方法 构建上调Atg7的慢病毒载体plenti6.3-Atg7,下调Atg7的慢病毒载体sh-Atg-1lv、sh-Atg-2lv,空载对照慢病毒载体sh-scramb-con lv、plenti6.3-GFP,分别转染肾癌786-0细胞系,未转染的786-0细胞系为空白对照。RT-PCR和Western blot检测各组Atg7的表达,研究plenti6.3-Atg7激活Atg7效率和sh-Atg-1lv、sh-Atg-2lv抑制Atg7效率。Western blot检测上述各组细胞LCII/LC3I蛋白比值,研究上调及下调Atg7对肾癌786-0细胞自噬的激活及抑制作用。结果 经过筛选,成功构建稳定上调Atg7的786-0/plenti6.3-Atg7xbx细胞系、稳定下调Atg7的786-0/sh-Atg-2lv细胞系、空载对照786-0/sh-scramb-con lv、786-0/plenti6.3-GFP细胞系。与空白对照组比较,Atg7上调组786-0细胞LCII/LC3I比值显著升高(3.31±0.12 vs.2.23±0.10 P<0.01),具有稳定的自噬激活作用;Atg7下调组的786-0细胞LCII/LC3I比值显著降低(1.45±0.11 vs.2.23±0.10 P<0.01),具有稳定自噬抑制作用。结论 上调Atg7对肾癌786-0细胞系具有自噬激活作用,下调Atg7对肾癌786-0细胞系具有自噬抑制作用。     

急性缺血缺氧诱导肝癌细胞自噬及其相关机制

目的:研究急性缺血/缺氧时肝癌细胞HepG2增殖率及自噬的变化,探讨自噬的作用及机制。方法 :以Western印迹法检测缺氧诱导因子-1(hypoxia induced factor-1,HIF-1)表达并确定体外模拟模型的可靠性;吖啶橙染色后采用荧光显微镜定性观察自噬;以自噬特异性蛋白LC3及P62(P62/SQSTM1)信号蛋白的变化表明自噬的诱导和可能的调控机制;以CCK8检测3-甲基腺嘌呤(3-MA)抑制自噬前后急性缺血/缺氧下HepG2细胞的增殖率变化。结果:急性缺血/缺氧2 h后,HepG2细胞显著表达HIF-1α蛋白,表明体外急性缺血/缺氧模型的可靠性。急性缺血/缺氧可快速诱导肝癌细胞HepG2产生自噬,继而出现HepG2细胞显著增殖活跃;3-MA抑制自噬后,可特异性抑制急性缺血/缺氧所诱导的HepG2细胞增殖;急性缺血/缺氧条件下HepG2细胞P62信号蛋白表达显著下调,自噬抑制后逐渐恢复正常表达水平。结论:自噬在肝癌体外急性缺血/缺氧过程中对肿瘤起到保护作用,其机制可能与P62蛋白的清除有关;抑制自噬可显著降低肝癌细胞增殖率。自噬可能成为肝癌治疗的新靶点。     

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.