椎间盘移植的实验研究

本实验研究目的在于：（１）建立间盘移植动物模型，（２）观察椎间盘移植术后不同时期Ｘ线、组织病理学、生物化学和生物力学变化。于１５只猴体上制备自体腰椎间盘移植模型，另有３只猴作为正常生物力学对照。结果表明移植间盘高度术后１～３个月呈下降趋势，４～１２个月呈恢复上升趋势。光镜下纤维环和终板软骨结构无明显改变，髓核中有部分细胞退变，同时亦有成软骨样纤维细胞的再生。术后２～４个月蛋白多糖和含水量呈下降趋势，６～１２个月有恢复；胶原含量２～６个月增加幅度较大，６～１２个月较平缓，其中髓核较纤维环明显。生物力学结果表明术后２个月时移植间盘活动度增大，术后４～１２个月恢复至正常水平。实验结果表明移植间盘在组织病理及生物化学方面有轻度退变倾向，同时又有一定的自我修复能力，生物力学上可满足生理活动功能需要。     

猴自体椎间盘移植的组织学研究

本实验观察了猴自体椎间盘移植术的不同时期间盘组织学变化。结果表明大体形态移植间盘髓核的含水景减少，呈较粘稠胶状，光镜下纤维环和终板软骨结构无明显变化，髓核中有部分细胞退变，同时亦有成软骨样纤维细胞再生。透射电镜发现间盘髓核中仍有脊索细胞存在，移植后不同时间组髓与纤维环中均可见部分细胞变性坏死。本实验成功地建立了椎间盘移植动物模型，为进上步深入研究提供了依据。     

同种异体椎间盘移植的实验研究

本研究是在自体椎间盘移植实验研究的基础上进一步通过Ｘ线、组织病理、生物学活性、生物化学和生物力学探索异体椎间盘移植是否可存活、功能及其归宿。１２只猴随机分为４组，移植术后３、６、９和１２个月分别处死检测。结果表明移植间盘高度术后下降，但１２个月时仍保持正常高度的６１．４％。光镜下未见明显排斥反应，终板和纤维环结构无明显改变，术后早期可见移植间盘终板软骨增生现象，髓核基质密度增大，成软骨样纤维细胞增生明显。３Ｈ－ｐｒｏｌｉｎｅ掺入较对照组明显增加。术后移植间盘的蛋白多糖和水含量降低，而胶原含量增加。生物力学动态变化表明术后早期移植间盘有失稳趋势，晚期则稳定性恢复。上述结果显示同种异体移植间盘可存活，生化代谢虽有变化但有一定的自限性，形态结构无明显改变，生物力学满足功能需要。     

椎间盘移植实验—生物化学研究

恒河猴１２只，于Ｌ＿（３￣４）行自体间盘移植手术。对术后不同时间移植间盘进行生化分析，测定了间盘组织的水、胶原和蛋白多糖含量变化，结果显示：术后２月蛋白多糖及水含量降低，胶原含量升高，髓核较纤维环变化明显。术后４月蛋白多糖及水含量进一步降低，胶原含量回升，与对照组已无统计学差异，水份和胶原含量较，４月无明显变化。提示：椎间盘移植后虽然在早朝有退变倾向，但在后期这种退变部分恢复。     

椎间盘移植实验──生物力学研究

本实验在６只猴体上制备自体椎间盘移植模型，观察术后不同时期生理载荷下屈伸活动时移植椎间盘的刚度（ｓｔｉｆｆｎｅｓｓ）变化。结果表明：术后２月，移植的Ｌ３～４椎间盘在整个屈伸活动中较上、下正常对照椎间盘的变形增大；术后４月，移植椎间盘变形接近正常对照椎间盘；术后６月，移植椎间盘刚度明显恢复。实验结果提示术后早期有腰椎节段性不稳倾向，中晚期稳定性恢复，移植椎间盘可满足生理活动功能需要。     

椎间盘细胞组织工程的研究进展

近年来体外椎间盘髓核各纤维环组织细胞培养技术的建立，特别是软骨组织工程研究的不断深入及自体椎间盘细胞移植修复髓核缺损动物实验的初步成功，为退变椎间盘的形态结构与生理功能的完全再生修复带来了希望。利用组织工程学修复退变的椎间盘是具有变革性意义的新的治疗探索。现就椎间盘组织工程学研究中的种子细胞、细胞支架、相关生长因子等方面的研究进展综述如下。     

椎间盘组织工程学研究进展

近年来体外椎间盘髓核和纤维环组织细胞培养技术的建立，特别是软骨组织工程研究的不断深入及自体椎间盘细胞移植修复髓核缺损动物实验的初步成功，为退变椎间盘的形态结构与生理功能的完全再生修复带来了希望。利用组织工程学修复退变的椎间盘是具有变革性意义的新的治疗探索。笔者就椎间盘组织工程学研究中的种子细胞、相关生长因子、细胞支架等方面的研究进展综述如下。     

胶原酶对山羊硬膜外移植自体椎间盘组织溶解作用的观察

目的：观察椎管内硬膜外腔注射胶原酶对山羊腰椎管内移植的自体椎间盘组织的溶解作用。方法：9只成年山羊，经腰椎后路右侧L6/7、左侧L3/4椎板间隙移植自体椎间盘组织于椎管内神经根腋部，随机选择向2个间隙移植物周围灌注胶原酶300U／0．3ml或生理盐水0．3ml。分别于术后1d、1周、2周处死动物，观察胶原酶灌注后椎管内移植的椎间盘组织的组织学变化情况。结果：灌注胶原酶1d时髓核组织基质明显溶解．1周时出现大量巨噬细胞浸润．髓核结构明显破坏，2周时被肉芽组织替代：而灌注生理盐水1d时髓核组织无明显变化，1周时髓核组织中出现大量淋巴细胞浸润，2周时出现纤维母细胞、成纤维细胞和巨噬细胞浸润。胶原酶对纤维环的溶解作用不明显。结论：硬膜外腔注射胶原酶能直接溶解椎管内髓核组织，并能激发机体炎症反应过程，加速髓核组织的破坏和吸收。     

腰椎间盘突出症手法治疗经验

腰椎间盘突出症是临床上常见病、多发病,按摩治疗本病效果良好。椎间盘是由软骨板、纤维环、髓核三部分组成,软骨盘是由椎间盘与上下椎体紧密相连的连片软骨组织。纤维环是构成椎间盘周围部分的一种坚韧的纤维组织,和上下连接软骨板紧密连接。髓核位于椎间盘的中心,稍偏后一点,是一种有水份的半胶体状组织。     

髓核对大鼠脊神经节非压迫性损伤的组织形态学研究

目的 观察硬膜外移植自体髓核后，大鼠脊神经节组织形态学的变化。方法 20只Sprague—Dawley(SD)雄性大鼠随机分成对照组和实验组，分别将自体肌肉混悬液和尾椎髓核混悬液注射到腰椎硬膜外腔，对脊神经节组织形态学进行观察。结果 在无机械压迫情况下，大鼠硬膜外移植自体髓核能使脊神经节组织形态产生明显改变。结论 髓核所致的炎性反应是引起脊神经节损伤和坐骨神经痛的重要原因之一。     

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.