骨髓间充质干细胞促进骨-肌腱结合部位早期愈合的动物生物力学实验研究

[目的]通过生物力学研究,观察骨髓间充质干细胞对骨-肌腱结合部愈合的影响.[方法]采用骨髓穿刺、全骨髓培养法获取兔骨髓间充质干细胞.24只18周龄新西兰大白兔随机分为2组,实验组将骨髓间充质干细胞与Pluronic F-127载体材料结合后,植入兔髌骨部分切除模型,对照组只进行手术,不植入细胞.在术后6、12、18周处死动物取标本(n=4)进行生物力学检测评估骨-肌腱结合部位的愈合恢复情况.[结果]生物力学结果显示相同时间点实验组拉断负荷及极限拉应力均大于对照组,差异有统计学意义(P<0.05),提示实验组恢复较对照组迅速.[结论]相同时间点实验组拉断负荷、极限拉应力均大于对照组.实验组的力学特性明显高于对照组.骨髓间充质干细胞可以促进骨-肌腱结合部细胞早期愈合,提高其力学特性.     

骨髓间充质干细胞对肌腱移植物在骨隧道内愈合效果及示踪的实验研究

[目的]观察骨髓间充质干细胞对肌腱移植物在骨隧道内愈合的影响,并为干细胞的标记示踪提供实验依据.[方法]采用贴壁分离筛选法获取大鼠的骨髓间充质干细胞(bone mesenchymal stem cells,BMSCs),用超顺磁性氧化铁(superparamagnetic iron oxide,SPIO)和DiI(1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate)对其标记.39只8周龄雄性SD大鼠随机分为两组,实验组21只,对照组18只.实验组在骨隧道内腱-骨结合面注入含双标的BMSCs和Pluronic F-127载体,对照组只注入载体,术后2、4、8周进行生物力学评估愈合效果,实验组2、4、8周组织冰冻切片荧光显微镜和手术后即刻、3、7 d行7.0 T MR示踪移植的BMSCs.[结果]SPIO、DiI能有效标记干细胞.实验组2、4、8周荧光显微镜观察在腱骨界面有DiI标记的阳性细胞存在.7.0 T MR未能在实验组腱骨界面观察到明显信号改变.生物力学最大拔出载荷实验组和对照组在术后2周无统计学差异,在4、8周实验组显著高于对照组(P<0.05).[结论]移植的骨髓间充质干细胞可以促进骨隧道内腱骨结合部的早期愈合,DiI能有效标记示踪干细胞,SHO能有效标记干细胞,但在该实验模型中7.0T MR可能不能活体示踪磁粒子标记的干细胞.     

骨膜促进骨-肌腱结点愈合的研究

[目的]探讨骨膜对骨-肌腱结合部位愈合的影响,通过实验证明骨膜促进骨-肌腱结合部位细胞增生,进而促进该部位愈合.[方法]48只18周龄新西兰大白兔随机分为2组,实验组将骨膜游离并植入兔髌骨部分切除模型中骨-肌腱结点中,对照组只进行手术,不植入骨膜.在术后4、8、12周处死动物取标本进行大体和组织学观察.[结果]大体观察可见实验组骨-肌腱结合部位愈合较早.组织学检查显示实验组术后4、8周骨-肌腱结合部组织愈合明显,以从松质骨再生和骨-肌腱愈合接点纤维软骨带的再生为特征,较对照组迅速,提示早期实验组恢复较对照组迅速.[结论]骨膜可以促进骨-肌腱结合部位细胞增生,增加细胞基质合成,促进新生骨和纤维软骨移行带形成,促进其愈合.     

骨髓间充质干细胞及其复合物对肌腱早期愈合影响的实验研究

[目的]探讨骨髓间充质干细胞(BMSCs)与纤维蛋白胶复合体对兔肌腱早期愈合的影响,为临床应用提供依据.[方法]家兔骨髓间充质干细胞离体培养、纯化、扩增后与纤维蛋白胶混合.36只家兔分为实验组和对照组,兔跟腱横断制作肌腱断裂模型.实验组应用自体BMSCs复合纤维蛋白胶移植于肌腱损伤区,对照组仅以纤维蛋白胶置于肌腱损伤区.分别于术后1周,3周,6周及12周对移植部位进行大体标本观察,细胞示踪、组织学检查、免疫组织化学检查、形态测定分析及生物力学测定.[结果]实验组相比对照组肌腱大体观察粘连差,肌腱活动性好.3周后纤维蛋白载体即降解,细胞示踪结果显示标记的骨髓间充质干细胞至少6周内仍可保持活性并存在于肌腱组织中,但之后逐渐扩散.3周时,实验组与对照组相比胶原纤维排列更为有序,且胞核形态结构更规则,但在6周及12周时,实验组与对照组胞核参数测定无统计学意义.3周时实验组比对照组具有更强的的生物力学特性,但之后则差别不明显.[结论]肌腱损伤后即给以腱内BMSCs复合纤维蛋白胶治疗可促进肌腱愈合早期组织形态学及生物力学修复.     

应用重组合异种骨促进前交叉韧带重建术后腱-骨愈合的研究

[目的]通过影像学、组织学及生物力学手段探讨重组合异种骨(RBX)对前交叉韧带重建术后腱-骨愈合的影响.[方法]25只新西兰白兔,利用双侧趾长伸肌肌腱重建前交叉韧带(ACL),其中一侧移植物两端固定有RBX,另一侧作为对照组,分别于术后2、6、12周取材,进行Micro-CT扫描,组织学染色(包括HE、甲苯胺蓝)以及生物力学检测,观察腱-骨之间愈合状况.[结果]影像学结果显示,术后6、12周RBX治疗组腱-骨之间的骨矿化组织密度(BMD)数值均高于对照组,并具有显著性差异;组织学结果显示,术后2周,RBX组腱-骨之间被大面积不规则分布的软骨样细胞填充;术后6周,治疗组的腱-骨之间已见大量成熟软骨细胞,并开始分泌基质.而对照组术后腱-骨间一直被纤维样结缔组织连接,至术后12周,治疗组部分标本出现类ACL正常肌腱止点.生物力学结果同样证实,RBX组的最大牵拉力均显著高于对照组.[结论]RBX可显著提高ACL重建术后腱-骨之间的愈合,较早恢复膝关节功能.     

放射性核素骨显像动态检测组织工程化骨血管化的价值

[目的] 放射性核素骨显像动态检测评价组织工程化骨血管化与骨代谢的价值.[方法] 取大白兔24只,抽取骨髓,行骨髓间充质干细胞分离、培养与骨向诱导.双侧股骨髁制作0.6 cm×1.2 cm的骨缺损,将诱导后的骨髓间充质干细胞与珊瑚羟基磷灰石复合植入左侧骨缺损处为实验组,右侧单纯植入珊瑚羟基磷灰石为对照组.术后4、8、12周分别行静态放射性核素骨显像检测,用ROI计数计算不同时间点的ROI平均计数.[结果] 结果术后4、8、12周实验组ROI计数(单位像素)均较对照组有显著性增高.实验组ROI计数随时间的延长,呈明显的上升趋势,术后8周开始增长放缓;对照组ROI计数术后8周增长缓慢,8周后开始增长加快,两组均在12周达到峰值.[结论] 骨髓间充质干细胞诱导后与珊瑚羟基磷灰石复合可有效的修复股骨髁松质骨缺损.放射性核素骨显像可动态检测组织工程化骨血管化及骨代谢变化.     

肌腱-骨块自体复合移植物嵌压固定法重建前交叉韧带的实验研究

[目的]研究肌腱-骨块自体移植物嵌压固定法重建前交叉韧带的组织形态学转归.[方法]以8只山羊膝关节为实验模型,用阶梯状联合钻1次成形建立股骨隧道呈倒置瓶颈状,以髌腱-胫骨结节骨块为移植物,在股骨隧道内行嵌压固定;在胫骨端骨桥打结固定.术后4、8、12和16周取材,分别进行放射学、大体形态和组织切片检查,观察隧道宽度变化及移植物的组织学转归.[结果]术后各时间点放射检查未见隧道扩大;HE染色检查显示12周后有明显的腱-骨连接形成,移植骨块与隧道形成骨性愈合.[结论]嵌压固定法重建前交叉韧带有利于移植物的愈合.     

骨形态发生蛋白2基因修饰自体骨髓间充质干细胞移植促进兔胫骨牵张成骨的实验研究

[目的]观察人骨形态发生蛋白2基因修饰的自体骨髓间充质干细胞移植对兔胫骨牵张成骨新骨形成的促进作用。[方法]48只新西兰白兔随机摸球法分为3组。建立牵张成骨动物模型,在固定期第2 d,实验组于牵张间隙注射人骨形态发生蛋白2基因修饰的自体骨髓间充质干细胞;对照组注射等量自体骨髓间充质干细胞;空白组不注射任何物质。[结果]在固定期2周及6周实验组牵张区在大体观察、HE染色、X线观察方面成骨质量均好于对照组和空白组。12周后取牵张成骨区标本作骨组织骨密度和生物力学测定,结果显示实验组新生骨质量较高,骨愈合情况要优于对照组和空白组。[结论]骨形态发生蛋白2基因修饰的自体骨髓间充质干细胞移植能有效提高兔胫骨牵张成骨新骨形成质量。     

间充质干细胞体内成骨的实验研究

[目的]探讨间充质干细胞在体内的成骨能力。[方法]从羊髂嵴处抽取10～15ml骨髓组织，用Pereoll分离液按梯度离心法分离出间充质干细胞，培养、增殖后种植在多孔β-磷酸三钙上，构建组织工程化骨，植入8只羊的左后肢跖骨缺损区（长21mm）作为实验组；单纯植入多孔β-磷酸三钙陶瓷材料的8只羊作为对照组；分别在术后6、12、24周处死动物行放射学、组织学和生物力学检测。[结果]放射学和组织学检测，术后6周实验组即可见有新骨生成，对照组则无明显新骨生成；骨缺损部位新生骨样组织、编织骨和板状骨出现的时间实验组也都较对照组早，并且不经软骨介导即能直接成骨，而对照组从两端以“爬行替代”方式成骨。术后24周，放射学和生物力学检测显示实验组骨缺损几乎完全修复，对照组只有部分愈合。[结论]间充质干细胞不仅在体外具有良好的增殖能力，回植人体内后仍然具有良好的成骨能力，不需经过软骨过程就能直接形成新骨，显示了间充质干细胞作为骨组织工程种子细胞良好的应用前景。     

骨-肌腱结合部损伤愈合研究进展

骨-肌腱结合部愈合过程中重建正常的纤维软骨移行带是恢复肌肉-肌腱-骨关节间动力传导功能的关键.纤维软骨带结构复杂,再生能力较差,致使骨-肌腱结合部的再生十分困难而缓慢.研究骨-肌腱结合部愈合过程中特征性结构纤维软骨移行带的修复机制,对指导临床治疗及术后康复锻炼具有深远意义.影响骨-肌腱结合部愈合过程的因素很多,手术重接技术、局部固定方法、局部生物力学环境、术后康复锻炼方案等,均对骨-肌腱结合部愈合及纤维软骨移行带重建产生重要影响.该文就近年骨-肌腱结合部愈合相关研究进展作一综述.     

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.     

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.     

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.     

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.