亲和素-生物素黏附系统修饰纳米纤维构建组织工程神经的实验研究

目的 观察亲和素-生物素黏附系统(avidin-biotin binding system,ABBS)快速黏附雪旺细胞(SCs)对组织工程神经促进神经再生的影响.方法 以坐骨神经缺损10 mm作为实验模型.取40只Wistar大鼠分成A、B、C、D4组,每组10只.A组:自体神经移植修复组;B组:空白对照组,用聚乳酸己内酮共聚物[ Poly(L-lactic acid-co-epsilon-caprolactone),P(LLA-CL)]支架修复神经缺损;C组:P(LLA-CL)支架上用普通方法黏附雪旺细胞修复神经缺损;D组:P(ILA-CL)支架上用ABBS法黏附雪旺细胞修复神经缺损.术后3个月,检测坐骨神经功能指数、神经传导速度、再生神经轴突及髓鞘厚度,评估ABBS对于促进神经再生的影响.结果 C组与D组的神经修复效果无差别.虽然修复效果不及A组,但是均明显好于没有雪旺细胞的B组.结论 ABBS在动物体内实验中未对组织工程神经促进神经再生造成不利影响,是一种可靠的细胞快速黏附方法.     

肺腺癌A549细胞CD133~+CD44~+表型在裸鼠体内成瘤能力的研究

目的 探讨肿瘤标志物CD133和CD44的表达与人肺腺癌A549细胞株在裸鼠体内形成肿瘤能力的关系.方法 使用单细胞克隆的方法 ,筛选出能够持续增殖分裂的肿瘤细胞,应用免疫荧光方法 和流式细胞仪检测CD133和CD44在具有增殖分裂能力的A549细胞和普通A549肿瘤细胞的表达情况;按表达结果 对A549细胞进行分组,应用单克隆方法 对各组细胞进行培养,并按不间密度注射于裸鼠皮下,观察各个组别的成瘤能力.结果 (1)在倒置显微镜下观察肿瘤细胞生长情况,发现多数细胞死亡,1周后仅有4.11%的细胞能够增殖分裂形成克隆.(2)具有增殖分裂能力肿瘤细胞的免疫荧光结果 :CD133阳性率为19.0%,CD44阳性率为57.0%;普通A549肿瘤细胞免疫荧光结果 :CD133阳性率为2.5%,CD44阳性率为34.0%;具有分裂增殖能力的肿瘤细胞CD133和CD44阳性表达率显著高于普通A549肿瘤细胞(P<0.01).(3)裸鼠体内成瘤能力实验提示:CD133~+CD44~+(A组)细胞成瘤能力显著高于CD133~-CD44~-(B组)、CD133~-CD44~+(C组)和CD133~+CD44~-(D组)细胞(P<0.05);裸鼠瘤块病理检查证实均为腺癌,各脏器检查未发现转移:在接种CD133~+CD44~+(A组)细胞的瘤块组织中发现除了有CD133~+CD44~+细胞外,还有CD133~-CD44~-细胞.结论 肺腺癌A549细胞株中CD133~+CD44~+细胞在裸鼠体内的成瘤能力显著高于其他细胞.     

自体软骨细胞复合Ⅰ型胶原支架体外动态培养的实验研究

[目的]比较体外静态与动态培养两种方式对培养人关节软骨细胞复合Ⅰ型胶原支架材料的效果,从而探索体外构建移植物用于治疗关节软骨缺损的适宜条件及方式。[方法]分离培养人关节软骨细胞,P2代软骨细胞接种于Ⅰ型胶原支架,随机分为3组,A组:静态培养;B组:动态培养;C组:单层培养。采用倒置相差显微镜、荧光显微镜、SEM、HE染色观察细胞在支架上的分布、黏附、生长及形态特点,实时荧光定量PCR检测软骨细胞表型特异基因Ⅱ型胶原的表达情况。[结果]体外单层培养的软骨细胞(P2)以多角形为主,Ⅱ型胶原蛋白表达阳性,提示P2代细胞表型维持良好;与A组比较,B组细胞数量较多且分布均匀,细胞形态较均一,以多角形为主;A、B组样本大体结构及内部孔隙结构均保持完整,孔隙内均可见细胞黏附,B组孔隙内细胞数量及细胞外基质优于A组;A、B组的Ⅱ型胶原基因mRNA表达水平较单层培养组明显增加。[结论]软骨细胞复合Ⅰ型胶原支架体外动态培养较静态培养可明显促进细胞增殖及细胞外基质分泌。因此,动态培养有望成为体外构建自体软骨细胞移植术所需移植物的一种有效方法。     

壳聚糖多孔支架复合BMSCs移植修复大鼠创伤性脑损伤的实验研究

目的探讨壳聚糖多孔支架复合BMSCs移植修复大鼠创伤性脑损伤(traumatic brain injury,TBI)的可行性。方法取成年SD大鼠胫骨及股骨骨髓,采用全骨髓贴壁培养法分离培养BMSCs,并传代。取第3代细胞行表面抗原CD29、CD45鉴定及BrdU标记。采用冷冻干燥法制备壳聚糖多孔支架,并与BrdU标记的第3代BMSCs进行体外共培养;扫描电镜观察细胞黏附情况,MTT法检测支架内细胞生长情况。取50只成年SD大鼠,随机分为A、B、C、D、E组(n=10)。A～D组大鼠采用Feeney自由落体打击致伤原理制备TBI模型,造模后72 h分别移植BMSCs-壳聚糖多孔支架复合体、BMSCs、壳聚糖多孔支架和完全培养基;E组为假手术组。于造模前及造模后1、7、14、35 d,各组大鼠行改良神经功能缺损评分(modified neurological severity scores,mNSS);造模后进行Morris水迷宫测验,包括定位航行测验(造模后31～35 d连续5 d检测潜伏期)及空间探索测验(造模后35 d检测穿越平台次数);造模后36 d取标本行HE染色、BrdU与高分子量神经丝蛋白免疫组织化学双重染色以及BrdU与神经胶质酸性蛋白免疫组织化学双重染色,观察大鼠脑损伤区BMSCs的迁移与分化情况。结果流式细胞仪检测示第3代BMSCs的CD29阳性率为98.49%,CD45阳性率仅为0.85%;扫描电镜示支架-细胞共培养48 h后,BMSCs呈梭形并分泌细胞外基质黏附于支架上;MTT法检测示壳聚糖多孔支架对BMSCs的增殖分化无不良影响。TBI造模后35 d,A组大鼠mNSS评分、定位航行测验的潜伏期显著低于B、C、D组,空间探索测验的穿越平台次数显著高于B、C、D组,差异均有统计学意义(P0.05);A、E组间上述指标比较差异均无统计学意义(P0.05)。HE染色示A组壳聚糖多孔支架已部分降解,其与脑组织融合良好,修复程度优于B、C、D组。免疫组织化学双重染色结果示,A组移植的BMSCs存活、分化为神经元和神经胶质细胞,并迁移至正常脑组织内,修复程度优于B、C、D组。结论壳聚糖多孔支架介导的BMSCs移植能够明显改善大鼠TBI后的神经功能,亦能抑制大鼠脑损伤区胶质瘢痕形成,并可使BMSCs在脑损伤区存活、增殖和分化为神经细胞。     

骨髓间充质干细胞在β3转化生长因子联合胰岛素样生长因子-1定向诱导下的软骨组织工程

目的探讨β3转化生长因子（TGF-β3）在诱导骨髓间充质干细胞（mesenchymal stem cells,MSCs）向软骨细胞分化中胰岛素样生长因子-1（IGF-1）的作用以及在软骨组织工程中的应用。方法在体外用TGF—β3或（和）IGF-1诱导藻酸钠微球中的MSCs向软骨细胞定向分化,免疫组织化学、逆转录-聚合酶链反应（RT—PCR）检测Ⅱ型胶原和聚集蛋白聚糖（aggrecan）的表达,Western印迹法检测Sox9蛋白的表达,激光共聚焦显微镜和扫描电镜观察该软骨细胞在壳聚糖支架上的生长。结果TGF-β3。能诱导藻酸钠微球中的MSCs表达软骨特异性的Ⅱ型胶原、聚集蛋白聚糖和Sox9,IGF-1能显著性地增强这种作用（P〈0．05）。Ⅱ型胶原、聚集蛋白聚糖和Sox9之间的相关系数分别为0．95和0．91。诱导的软骨细胞能在壳聚糖支架上黏附、迁徙、增殖。结论在TGF-β3诱导MSCs分化成软骨细胞地过程中,IGF-1可能通过促进Sox9的表达起到协同作用。诱导分化后的软骨细胞与壳聚糖复合支架表现出良好的组织相容性。     

人Ⅰ型前胶原基因反义寡核苷酸抑制增生性瘢痕成纤维细胞胶原合成

目的 探讨阳离子脂质体介导Ⅰ型前胶原基因(Col Ⅰ A1)反义寡核苷酸(antisense oligodeoxyneucleotide,ASODN)转染对人增生性瘢痕成纤维细胞Col Ⅰ A1表达的影响.方法 取患者自愿捐赠瘢痕组织,采用组织块法培养人增生性瘢痕成纤维细胞并传代.于6孔板内按32.25×104个/孔的密度接种第4代细胞,根据转染液不同分为4组:A组为脂质体加Col Ⅰ A1 ASODN,B组为Col Ⅰ A1 ASODN,C组为脂质体,D组为空白对照.转染后8 h,1、2、3、4 d分别提取细胞总RNA,行RT-PCR后测定Col Ⅰ A1 mRNA表达量;胃酶消化法提取ECM中Col Ⅰ A1蛋白,ELISA测定其浓度.结果 扩增产物经琼脂糖凝胶电泳榆测显示条带清晰,无杂带、明显的引物二聚体及拖尾现象.Col Ⅰ A1 mRNA相对表达量:转染后8 h,A组小于B、C、D组,B、C组小于D组,比较差异均有统计学意义(P＜0.05);B、C组间比较筹异无统计学意义(P＞0.05);转染后1 d,A、B组小于C、D组(P＜0.05),A、B组间和C、D组间比较差异无统计学意义(P＞0.05):转染后2 d,各组间比较差异均有统计学意义(P＜0.05);转染后3、4 d,A组小于B、C、D组,B组小于C、D组(P＜0.05),C、D组间差异无统计学意义(P＞0.05).Col Ⅰ蛋白浓度:转染后8 h,A组小于B、C、D组,B、C组小于D组,比较差异均有统计学意义(P＜0.05),B、C组间差异无统计学意义(P＞0.05);转染后1 d,各组间比较差异均有统计学意义(P＜0.05);转染后2、3、4 d,A、B组小于C、D组,C组小于D组(P＜0.05),A,B组间差异无统计学意义(P＞0.05).结论 Col Ⅰ A1 ASODN抑制Col Ⅰ A1 mRNA和蛋白表达;阳离子脂质体作为载体有增强效果,促进ASODN进入细胞并在核内分布.     

nHA-PLGA支架材料与兔软骨细胞体外培养的生物相容性研究

目的 研究新型多孔复合支架材料纳米羟基磷灰石(nHA)-聚乳酸羟基乙酸共聚物(PLGA)的生物相容性,探讨其作为骨组织工程支架的可行性.方法 将胎兔膝关节软骨细胞接种于制备的nHA-PLGA复合支架上,体外共同培养后采用四甲基偶氮唑蓝(MTT)法检测软骨细胞增殖活性,倒置荧光显微镜、扫描电镜观察支架材料表面和孔隙内软骨细胞黏附情况,流式细胞术检测软骨细胞周期情况.结果 实验组(A组)复合支架材料上细胞增殖活性与空白对照组(B组)相比,无统计学差异(P＞0.05);倒置荧光镜、扫描电镜观察显示A组细胞在复合支架材料表面和孔隙内大量黏附、生长,其数量随着共培养时间增加呈几何级增长;流式细胞仪检测显示A组与B组细胞周期差异无统计学意义(P＞0.05).结论 nHA-PLGA多孔复合支架生物相容性好,是一种性能良好的骨组织工程支架材料.     

胶原-透明质酸-硫酸软骨素复合三维支架体外构建组织工程软骨的实验研究

目的探讨以胶原(collagen,Col)透明质酸(hyaluronic acid,HA)硫酸软骨素(chondroitin sulfate,CS)为支架材料构建组织工程软骨的可行性.方法以乙基-(3-二甲基氨基丙基)碳化二亚胺盐酸盐为交联剂通过冷冻干燥的方法制备Col-HA-CS复合支架及单纯Col支架.通过扫描电镜、HE染色对Col-HA-CS复合支架材料形态进行观察.分离培养幼兔关节软骨细胞,将体外扩增的软骨细胞接种在两种支架上,通过组织学、扫描电镜观察软骨细胞在支架上的生长形态;通过生物化学功能检测细胞-支架复合物中DNA、糖胺聚糖(glycosaminoglycan,GAG)含量;RTPCR方法检测在Col HA CS复合支架上的软骨细胞ColⅡ的表达情况.结果软骨细胞在Col-HA-CS复合支架材料上增殖分化良好,并保持软骨细胞特异的分化ColⅡ表型,培养21 d后已有软骨样组织形成,出现软骨陷窝.DNA和GAG含量测定显示软骨细胞在复合支架上随时间增加逐渐扩增并分泌大量的GAG,含量明显高于单纯Col支架材料,差异有统计学意义(P＜0.05).结论 Col-HA-CS复合支架材料可为软骨细胞生长分化及组织形成提供一个良好的环境,在软骨组织工程的支架材料领域有较广泛的应用前景.     

阿仑膦酸钠对IL-1β体外诱导培养的大鼠膝关节软骨细胞影响的实验研究

目的二膦酸盐类药物可抑制骨重塑,通过观察阿仑膦酸钠(alendronate,ALN)对IL-1β体外诱导培养的大鼠膝关节软骨细胞的影响,探讨ALN治疗骨性关节炎(osteoarthritis,OA)的可行性。方法取15只1月龄SPF级SD大鼠(雌雄不限,体重100～150g)膝关节软骨,体外培养软骨细胞并传至第3代。倒置相差显微镜下观察细胞形态并进行鉴定。将第3代软骨细胞分为3组:空白对照组(A组)软骨细胞用常规DMEM完全培养液培养5d;IL-1β诱导组(B组)软骨细胞以10ng/mL重组人IL-1β培养2d后更换为常规DMEM完全培养液培养3d;IL-1β诱导后加ALN培养组(C组)软骨细胞以10ng/mL重组人IL-1β培养2d后更换为浓度为1×10-6mol/L的ALN培养3d。培养后取各组细胞进行免疫细胞化学染色及实时PCR检测,观察细胞中Ⅱ型胶原(collagen typeⅡ,ColⅡ)、基质金属蛋白酶13(matrix metalloproteinase13,MMP-13)和β-连环蛋白(β-catenin)的表达水平。结果甲苯胺蓝染色示培养的细胞呈异染性,证实为软骨细胞。免疫细胞化学染色显示:A、B、C组ColⅡ表达积分吸光度(IA)值分别为15.3770±0.5718、5.4632±0.4504、10.2907±0.4992,C组高于B组,但低于A组,差异有统计学意义(P<0.05);MMP-13表达IA值分别为2.7775±0.1996、6.9981±0.3297、3.0686±0.2056,C组明显低于B组(P<0.05),但与A组比较差异无统计学意义(P>0.05);β-catenin表达IA值分别为4.3903±0.5519、11.7999±0.3487、6.6117±0.3818,C组低于B组,但高于A组,差异均有统计学意义(P<0.05)。实时PCR检测示,C组ColⅡmRNA表达高于B组,MMP-13及β-catenin的mRNA表达低于B组,比较差异均有统计学意义(P<0.05);ColⅡ和β-catenin mRNA表达高于A组,MMP-13mRNA表达低于A组,比较差异均有统计学意义(P<0.05)。结论 ALN可能通过抑制IL-1β诱导的大鼠膝关节软骨细胞中ColⅡ的降解并下调MMP-13及β-catenin因子的表达,对软骨细胞具有一定的保护作用。     

肿瘤干细胞表型CD44和CD24在乳腺癌骨转移模型骨髓中的表达及意义

目的 探讨人乳腺癌细胞转移到人骨的乳腺癌骨转移小鼠模型中骨髓肿瘤干细胞表型CD44和CD24的表达及其意义.方法 50只SCID小鼠随机分成实验组和对照组,其中实验组鼠背部植入人骨后随机均分3亚组:A组(MDA-MB-231干细胞亚群1×105个/只)、B组(同A组细胞1×106个/只)和C组(MDA-MB-231亲代细胞1×106个/只);对照组设为D组(阳性对照,未植入人骨,同C组细胞直接注射)、E组(阴性对照,植入人骨,生理盐水注射).各组8周后取人骨、鼠骨等行常规HE染色及CK、CD44、CD24、CXCR4、OPN免疫组织化学标记.Real-time PCR检测CD44、CXCR4、OPN的mRNA水平.结果 B组骨转移率最高(77.8%,P＜0.05).B组中人骨转移灶CD44、CXCR4、OPN抗原表达高于C、D组骨中的表达(均有P＜0.05);CD24抗原则在A、B组人骨转移灶中低表达与C、D组骨中的高表达无统计学意义(P＞0.05).B组CD44mRNA表达水平是C组的15.2倍、D组的21.1倍;B组CXCR4mRNA表达水平是C组8.4倍、D组28.4倍;B组OPN-mRNA表达水平是C组4.8倍、D组11.6倍;而B组CD24的mRNA表达显著低于C、D组(均为30%).结论 利用MDA-MB-231肿瘤干细胞亚群(CD44+/CD24-)可制备高转移率的"人源性"乳腺癌骨转移模型,其机制可能与CD44高表达有关.骨转移相关基因CXCR4、OPN转录上调可能参与其过程.     

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.     

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.     

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.