微创针刺旋切制备兔椎间盘退变模型

目的探讨微创针刺旋切制备兔椎间盘退变(intervertebral disc degeneration,IDD)模型的可行性。方法取40只新西兰大白兔,雌雄不限,体质量(2.9±0.3)kg;随机分为对照组和实验组(n=20)。对照组不予处理;实验组采用18G穿刺针在C臂X线机引导下经皮侧后方穿刺进入L4、5、L5、6椎间盘内,旋切髓核组织以促进椎间盘的退变。术后4、8、12、16周行大体观察、MRI观察并根据Pfirrmann分级法评价椎间盘退变情况,然后处死动物取材行Masson染色和番红O染色观察。结果实验组髓核组织颜色较对照组暗,弹性降低。对照组MRI T2加权像椎间盘信号强度早期未见明显改变,后期略减弱;实验组椎间盘信号强度随时间延长呈减弱趋势。根据Pfirrmann分级法评价椎间盘退变程度,两组随时间延长椎间盘退变程度均逐渐加重(P0.05);两组间比较除术后4周差异无统计学意义(P0.05)外,其余术后各时间点实验组椎间盘退变程度较对照组严重(P0.05)。Masson染色示随时间延长,对照组纤维环出现排列不规整,但结构仍完整;实验组纤维环排列紊乱,甚至出现断裂现象。番红O染色示对照组髓核细胞未见明显减少,实验组髓核细胞明显减少。结论微创针刺旋切法可成功制备兔IDD模型。     

大鼠尾椎椎间盘退变静态压力模型的构建

目的采用静态压力构建稳定的大鼠尾椎椎间盘退变模型。方法将40只12周龄大鼠随机分为静态压力组和针刺组,每组20只。静态压力组:在尾椎C_(4~7)椎体上安装静态压力环形外固定支架,压缩的4根弹簧施加的压强均为10 kPa,维持8周。针刺组:采用16 G针头刺入尾椎C_4/C_5/C_6/C_7椎间盘,限制损伤深度5 mm、朝向椎间盘中心,损伤后留置10 s。分别于术后8周进行组织病理学切片观察,采用秩和检验比较2组Thompson椎间盘退变病理分级。结果对2组大鼠尾椎共120个椎间盘髓核组织标本进行病理分级,统计结果显示静态压力组退变级别明显高于针刺组,差异有统计学意义(P0.05)。结论采用静态压力构建的椎间盘退变模型稳定可靠,较传统针刺模型具有优势,可为临床椎间盘退变研究提供可靠的动物模型。     

大鼠正常与退变性髓核突出导致神经根性疼痛的对比研究

目的探讨正常与退变髓核突出对大鼠疼痛阈值以及背根神经节中TNF-α表达的影响,研究椎间盘退变与神经根性疼痛之间的关系。方法72只大鼠随机分为4组:正常对照组(n=18)、假手术组(n=19)、正常髓核(N-NP)组(n=16)和退变髓核(P-NP)组(n=19)。对P-NP组大鼠利用尾椎椎间盘纤维环穿刺的方法建立椎间盘退变模型。分别取出N-NP组和P-NP组大鼠自体的正常髓核与退变髓核组织,置于手术显露后的腰5左侧神经根处,建立髓核突出致神经根性疼痛动物模型。采用行为学测试的方法分别观察各组大鼠术前1天,术后1、4、7、10、14、21天机械刺激阈值与热刺激阈值的变化;采用免疫组化方法分别检测术后第4、14天各组大鼠背根神经节中TNF-α的表达。结果行尾椎间盘纤维环穿刺后2周,组织学与MRI检查均证实椎间盘组织发生明显退变。对照组和假手术组动物未出现明显的痛觉过敏现象,N-NP组和P-NP组大鼠机械性刺激阈值均显著下降,该痛觉过敏现象持续至术后2周消失;与正常髓核组织相比,退变髓核所致机械性刺激阈值下降程度更为严重。各实验组均未发生热刺激阈值的规律性变化。术后第4、14天对照组和假手术组背根神经节中未见TNF-α明显表达,而正常及退变髓核组TNF-α表达量均显著升高。结论大鼠尾椎纤维环穿刺是建立大鼠椎间盘退变模型的一种有效方法。与正常髓核组织相比,发生退变的髓核组织可导致神经根性疼痛的加重,提示椎间盘退变过程中释放的炎症因子在疼痛的发生机制中可能起到了重要作用。     

1-磷酸鞘氨醇受体在不同退变程度髓核组织中的表达变化

目的 :比较不同退变程度人椎间盘髓核组织中3种1-磷酸鞘氨醇受体(S1PR1/2/3)表达水平的差异,探讨椎间盘中S1PR表达水平与椎间盘退变的关系。方法:收集腰椎间盘退行性病变患者手术切除的椎间盘组织,其中轻度退变(Pfirrmann分级Ⅳ级)22例,严重退变(Pfirrmann分级Ⅴ级)14例;同时取6例无椎间盘退变患者(单纯腰椎椎体骨折,Pfirrmann分级Ⅱ级)手术切除的椎间盘组织作为对照组;通过HE染色以及Saf-O染色观察不同退变程度椎间盘的组织学变化,免疫组化检测不同退变程度组织中的S1PR表达水平;Ⅱ型胶原酶消化分离提取原代髓核细胞,通过Real-time PCR、Western-bolt检测不同退变程度椎间盘髓核细胞中S1PR的表达水平,并通过细胞免疫化学方法对S1PR进行定位。结果:HE染色及Saf-O染色结果显示退变椎间盘的纤维环出现破损,髓核细胞形成明显的集落,细胞外基质减少。免疫组化结果显示正常和轻度退变的髓核组织中3种受体(S1PR1/2/3)都有表达,严重退变的组织中表达极弱;Real-time PCR结果显示对照组髓核细胞中S1PR1/2/3的m RNA表达水平分别是严重退变组的5.34±0.52倍、7.25±0.04倍、1.92±0.06倍,轻度退变组S1PR1/2/3的m RNA表达水平分别是严重退变组的4.35±2.45倍、4.96±3.44倍、2.19±0.82倍;Western-blot发现对照组和轻度退变组髓核细胞中S1PR1/2/3均有表达,严重退变组表达水平较低;免疫细胞化学显示S1PR主要集中在髓核细胞的细胞质和细胞膜上。结论:髓核组织中主要表达S1PR1/2/3,在严重退变的髓核组织和细胞中其表达水平明显下降,S1P及其受体可能参与椎间盘髓核组织的退变过程。     

应用微创技术建立恒河猴腰椎间盘早期退变模型

目的 应用CT定位,经皮穿刺纤维环诱导恒河猴腰椎间盘退变,建立灵长类动物腰椎间盘早期退变模型.方法 恒河猴13只,随机分为三组:(1)造模组:在CT定位下,用20G穿刺针从左侧后方入路经皮穿刺L1,2:(n=12),L2,3、L3,4、L4,5、L5,6(n=13)椎间盘的纤维环全层至椎间盘髓核正中,共64个椎间盘.(2)穿刺对照组:15G穿刺针穿刺1只猴的L1,2椎间盘.(3)正常对照组:L6,7,L7-S1,共26个椎间盘.造模前及造模后4、8、12周对各组椎间盘行MRI检查,并行HE、Masson、番红O、免疫组织化学染色组织学观察.结果 (1)MRI:20G穿刺针穿刺的造模组椎间盘造模前及造模后4、8、12周,椎间盘信号强度按Pfirmann分级均为Ⅰ级.15G穿刺针穿刺椎间盘4周时信号降低(Pfirrmann Ⅲ级),8周时为黑色椎间盘(Pfirmann Ⅳ级).正常对照组椎间盘为Pfirmann Ⅰ级.(2)组织学:造模组椎间盘造模后4周未见改变,8周时HE染色示髓核内细胞数减少,12周时较为明显.Masson染色4周未见改变,8周时各层纤维间出现裂隙,12周时裂隙增宽.番红O染色见8、12周髓核内蛋白聚糖进行性减少.免疫组织化学结果显示4周和8周时同正常椎间盘比较差异无统计学意义(P＞0.05),12周时,Ⅱ型胶原合成减少(P＜0.05).15G穿刺对照组在8周时HE染色见髓核内细胞减少明显,Masson染色见纤维环各层间裂隙明显,呈波浪状.番红O染色示髓核内蛋白聚糖数量明显减少.免疫组织化学染色示Ⅱ型胶原合成减少.正常对照组在各时间点未见到形态学改变.结论 20G穿刺针可以诱发椎间盘缓慢进展的轻度退变.MRI平均信号强度观察椎间盘轻度退变时,不是敏感的指标,需要依靠组织学证实.     

LOX在人体退变椎间盘髓核组织中的表达及临床意义

目的探讨赖氨酰氧化酶(LOX)在人体退变椎间盘髓核组织中的表达及其临床意义。方法选取自2018-01—2018-12诊治的22例腰椎间盘突出症患者作为观察组,将4例同期突发创伤导致腰椎椎体骨折行手术摘除椎间盘的年轻患者作为对照组。按照椎间盘Pfirrmann分级分组,对照组为Ⅰ级(A组);观察组细分为4组,B组为Ⅱ级,C组为Ⅲ级,D组为Ⅳ级,E组为Ⅴ级。取各组椎间盘髓核组织行免疫组化、Western Blot、PT-PCR检测。结果观察组髓核细胞数量及细胞外基质成分明显少于对照组。LOX在髓核细胞中的阳性表达率与Pfirrmann分级、年龄呈负相关。各组LOX蛋白表达量:A组2.69±0.24,B组2.24±0.32,C组1.34±0.19,D组1.30±0.32,E组1.01±0.12。各组LOXmRNA表达量:A组1.06±0.03,B组0.83±0.07,C组0.71±0.09,D组0.53±0.09,E组0.27±0.05。随着椎间盘退变程度加重,髓核组织LOX蛋白表达水平、mRNA表达水平呈逐渐降低趋势。结论 LOX的蛋白及mRNA表达水平随着人体椎间盘退变程度加重而降低,LOX可能参与了人体椎间盘髓核组织退变的发生与发展过程。     

脐带华通胶间充质干细胞移植对退变椎间盘影响的实验研究

目的:探讨人华通胶间充质干细胞(Wharton′s jelly-derived mesenchymal stem cells,WJMSCs)移植对犬退变椎间盘的影响。方法:从新生儿脐带中提取WJMSCs,取增殖良好的第3代细胞,用含有绿色荧光蛋白的腺相关病毒(r AAV2-EGFP)感染标记细胞。选择20只健康成年比格犬作为实验动物,使用穿刺抽吸髓核组织法建立椎间盘退变模型(L4/5、L5/6、L6/7)。4周后将犬各节段椎间盘进行分组:L3/4为对照组(A组);L4/5为退变组(B组);L5/6为注射组(C组),注射生理盐水;L6/7为移植组(D组),移植绿色荧光蛋白标记的WJMSCs细胞悬液。造模术前、术后4、8、12、24周行腰椎X线及MRI检查。24周后处死动物取材进行冰冻切片荧光、HE染色及番红O染色等组织学检测,提取髓核组织总RNA,反转录后行Real Time PCR检测,观察蛋白多糖、Ⅱ型胶原、SOX-9及Ⅰ型胶原基因表达变化。结果:分离培养的WJMSCs贴壁生长,呈梭形形态,r AAV2-EGFP病毒感染后第3天表达绿色荧光。影像学检查结果显示各组椎间盘高度指数及相对灰度指数在造模术前、术后第4周无统计学差异,术后8、12、24周,D组椎间盘相对高度指数及相对灰度指数较B、C组高(P0.05),比A组低(P0.05)。术后24周,D组髓核组织冰冻切片内能够检测到GFP阳性的WJMSC细胞,HE染色显示D组髓核组织退变比B组和C组轻,番红O染色结果显示D组染色较B组和C组深,基因表达检测结果显示D组Ⅱ型胶原、蛋白多糖及SOX-9基因表达比B、C组高(P0.05),但比A组低(P0.05)。结论:人WJMSCs移植入犬退变椎间盘内能够存活,促进椎间盘细胞外基质Ⅱ型胶原及蛋白多糖合成,维持椎间盘高度及髓核含水量,能够有效延缓椎间盘退变进展。     

移植骨髓间充质干细胞对兔退变椎间盘髓核细胞凋亡的影响

目的 观察骨髓间充质干细胞(MSCs)移植对兔退变椎间盘髓核细胞凋亡的影响.方法 以各兔L2/3、L3/4、L4/5、L5/6节段分为正常组、退变组、成纤维细胞(SFs)移植对照组、MSCs移植治疗组.MSCs和SFs分别经绿色荧光蛋白(GFP)转染后,注射植入退变椎间盘的髓核.通过透射电镜观察退变椎间盘凋亡髓核细胞形态;用实时定量聚合酶链反应(PCR)检测退变组织中髓核细胞凋亡相关基因bcl-2和box mRNA的表达;免疫荧光法标记髓核细胞凋亡相关蛋白Caspase-3,并通过TUNEL法标记凋亡髓核细胞,激光共聚焦显微镜检测髓核细胞凋亡蛋白表达率和细胞凋亡比率.结果 透射电镜下,退变椎间盘中凋亡髓核细胞呈现出核染色质边集,空泡形成,核膜断裂,凋亡小体形成等变化.MSCs移植治疗组bcl-2 mRNA的表达量高于退变组和SFs移植对照组(P<0.05),bax mRNA的表达量与退变组差异无统计学意义(P>0.05).MSCs移植治疗组细胞凋亡率和Caspase-3表达率均高于正常组[细胞凋亡率分别为(16.75±2.14)%和(6.86±1.08)%;Caspase-3表达率分别为[(20.34±1.03)%和(6.09±0.77)%](P<0.05),低于退变组和SFs移植对照组[细胞凋亡率分别为(31.87±4.16)%和(29.02±2.16)%;Caspase-3表达率分别为(31.50±3.78)%和(30.20±4.93)%](P<0.05).结论 髓核细胞凋亡在椎间盘退变过程中起重要作用.MSCs移植能有效抑制椎间盘髓核细胞凋亡,延缓椎间盘退变过程.     

大鼠增龄过程中髓核组织Beclin-1和微管相关蛋白轻链3的表达及其意义

目的 探讨在增龄过程中SD大鼠髓核组织中Beclin-1和微管相关蛋白轻链3(MAPLC3)的表达及其意义.方法 3个月龄、12个月龄、24个月龄SD大鼠各8只,建立青年组、中年组和老龄组大鼠模型,苏木素-伊红(HE)染色检测椎间盘组织的退变;透射电镜检测髓核细胞中自噬体的表达;免疫组织化学染色和逆转录-聚合酶链反应(RT-PCR)法测定髓核组织中Beclin-1和MAPLC3的表达.结果 大鼠增龄过程可较好地体现椎间盘的退变变化;不同年龄组大鼠髓核细胞中均有自噬体的表达;Beclin-1和MAPLC3在不同年龄组SD大鼠髓核细胞中均有表达(0.42±0.05,0.47±0.06,0.52±0.05;0.34±0.06,0.39±0.05,0.46±0.09),且老龄组表达均较青年组高(P<0.01).Beclin-1和MAPLC3 mRNA在不同年龄组SD大鼠髓核组织中均有表达(0.86±0.12,0.93±0.14,1.01±0.13;1.09±0.06,1.15±0.07,1.33±0.11),且老龄组表达较青年组表达明显增高(分别为P<0.05和P<0.01).结论 自噬存在于椎间盘退变过程中,且MAPLC3与Beclin-1在椎间盘退变过程中的表达增加,提示自噬活性的增加可能与椎间盘退变的发展进程有关.     

外源性肿瘤坏死因子-α诱发兔椎间盘退变中β-catenin蛋白的表达及意义

目的 通过外源性肿瘤坏死因子(TNF)-α注射构建兔椎间盘退变动物模型,探讨该模型中β-catenin蛋白的表达及意义和炎性细胞因子在促进腰椎间盘退变过程中Wnt/β-catenin信号通路的作用.方法 选取12只健康成年日本白兔,雌雄随机,体质量2.5～3.0kg.手术暴露L2～5 3个间隙共36个椎间盘.随机分为4组,分别注入生理盐水、TNF-α 5 ng、TNF-α 10ng、TNF-α 20 ng,于术后第8周统一处死,取椎间盘髓核组织作苏木素-伊红(HE)-番红O染色病理切片进行形态学观察;各组分别随机选取4个椎间盘髓核组织标本,采用蛋白印迹法(Western blot)测定β-catenin蛋白含量并比较各组间差异.结果 HE-番红O染色病理切片显示,在5、10、20 ng组椎间盘组织中髓核细胞数量减少,正常网状结构破坏,细胞形态发生改变,出现肥大空泡样软骨细胞,组织基质蛋白聚糖含量明显降低,番红O淡染,生理盐水对照组椎间盘形态基本正常,无退变发生.蛋白印迹结果显示β-catenin蛋白含量在注射TNF-α组明显增加,各组吸光度比值分别为:0.142±0.036、0.351±0.041、0.472±0.052和0.710±0.063,组间差异有统计学意义(P＜0.05)且与TNF-α浓度相关.结论 通过外源性TNF-α盘内注射能够成功构建兔椎间盘退变动物模型,且退变程度与TNF-α呈浓度依赖性;在退变模型髓核组织中β-catenin蛋白含量增高且与TNF-α浓度正相关,提示炎症细胞因子触发了Wnt/β-catenin信号通路,在椎间盘退变过程中可能发挥了重要作用.     

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.     

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.