骨组织工程支架材料多孔碳酸钙陶瓷Ames试验

目的 对骨组织工程支架材料多孔碳酸钙陶瓷(PCCC)进行Ames试验以评价其潜在致突变性.方法 采用浸提法制备多孔碳酸钙陶瓷(PCCC)生理盐水浸提液.采用标准平板掺入法,计数TA97、TA98、TA100、TA102在4个不同浓度浸提液下,37℃培养48 h后的回复菌落数,测试其对鼠伤寒沙门菌的致突变比值(MR=实验组回变菌落数Rt/阴性对照组回变菌落数Rc).结果 阳性对照组各菌株回变菌落平均数均超过其相应阴性对照组回变菌落平均数的二倍以上(MRp＞2),多孔碳酸钙陶瓷(PCCC)浸提液各剂量组对鼠伤寒沙门菌的致突变比值MR均小于2.结论 多孔碳酸钙陶瓷(PCCC)不会引起鼠伤寒沙门菌的回复突变数增加,提示其无潜在致突变性.     

激光立体成形多孔钛对成骨细胞的影响及生物相容性研究

[目的]评价激光立体成形技术制备的多孔钛材料对成骨细胞生长的影响和其生物相容性。[方法]以DMEM培养液和无菌生理盐水作为浸提介质,对激光立体成形技术制备的多孔钛材料制取浸提液,并在加有此浸提液的培养基中培养成骨细胞,对照组加入等量DMEM培养液和无菌生理盐水,在倒置相差显微镜下观察细胞的生长情况;采用细胞计数试剂-8(CCK-8)法检测细胞增殖抑制情况以及黏附实验测定细胞黏附能力;对多孔钛分别进行四甲基偶氮唑蓝(MTT)法测定的细胞毒性试验、溶血试验以及短期全身毒性试验等生物相容性检测。[结果]1倒置显微镜观察显示,培养3 d后,发现成骨细胞在激光立体成形多孔钛组能够很好地粘附、生长和分化;CCK-8法和细胞黏附实验均证实,与对照组相比,激光立体成形多孔钛组中成骨细胞抑制率和黏附力均未受明显影响(P0.05);2激光立体成形多孔钛为USP毒性0级,即无细胞毒性;溶血率为3.00%,有良好的血液相容性;无短期全身毒性。[结论]采用激光立体成形技术制备的多孔钛材料有利于成骨细胞增殖,具有良好的生物相容性,在组织工程领域有着广阔的应用前景。     

新型脱细胞骨基质-壳聚糖复合支架的生物相容性研究

[目的]评价新型脱细胞骨基质-壳聚糖(ABECM/CS)骨组织工程复合多孔支架的生物相容性和安全性,为临床应用提供实验依据.[方法]采用联合脱细胞方法对猪股骨进行处理后制备脱细胞骨基质/壳聚糖骨组织工程复合支架.分离、培养兔骨髓间充质干细胞传代后进行实验.采用MTT法观察材料浸提液于1、3、5、7d时进行细胞毒性实验观察细胞的活性;将材料浸提液与稀释血混合离心后观察红细胞溶血情况,检测OD值计算相对溶血率;将材料浸提液经静脉注入兔体内进行热原实验,在规定时间内观察兔体温变化.[结果]细胞毒性实验显示,培养1、3、5、7d后各时间段内三组OD值两两比较(P＞0.05)无显著差异,表明材料无毒性.在溶血实验中观察实验材料的溶血率为3.0％,在标准值溶血率5％范围内,提示无溶血现象发生.热原实验结果显示每只兔体温升高均低于0.6℃,且3只兔体温升高总度数低于1.4℃,符合热原检测规定,复合材料无致热作用.[结论]经联合脱细胞处理制备的ABECM/CS复合支架无细胞毒性、无溶血反应、无热原性,具有良好的生物相容性和安全性,可作为构建组织工程骨的支架载体材料.     

锌修饰硅酸钙生物陶瓷涂层的体外生物相容性研究

目的 研究锌修饰硅酸钙生物陶瓷涂层的体外生物相容性,为该涂层临床应用的可行性提供实验依据。方法检测该涂层的物理表征;检测该涂层浸提液的离子浓度;用不同稀释比例的浸提液培养MC3T3-E1细胞,观察细胞形态,MTT法检测细胞相对增殖率,并检测细胞凋亡水平;测定溶血率。结果 该涂层浸泡72 h后,浸提液中钙、硅、锌离子浓度均明显升高;用不同稀释比例的浸提液培养的MC3T3-E1细胞都表现出正常的细胞形态,其中3.125%、6.25%组细胞量较多,相对增殖率高于阳性对照组,且细胞凋亡率低于阳性对照组(完全培养基);随浸提液浓度增加,可对细胞增殖产生轻度抑制作用,凋亡率逐渐升高;溶血试验结果显示,该涂层浸提液的溶血率为0.5%。结论 锌修饰硅酸钙生物陶瓷涂层没有细胞毒性、生物相容性好,具有作为骨植入体及其他生物材料表面改性的生物学基础。     

新型复合纤维蛋白胶的磷酸钙骨水泥的生物安全性研究

目的 研究新型复合纤维蛋白胶的磷酸钙骨水泥的生物相容性和生物安全性,探讨其用于临床修复骨缺损的可行性。方法 制备新型复合纤维蛋白胶的磷酸钙骨水泥,获取材料浸提液。选择急性毒性试验、溶血试验、微核试验、细胞毒性试验,对新型复合人工骨材料进行生物相容性和安全性评价。结果 该磷酸钙骨水泥材料浸提液未引起小鼠急性毒性反应;各实验组肉眼下未见明显溶血反应,溶血率0.05);浸提液对小鼠MC3T3成骨细胞的生长分化无明显影响,细胞毒性分级为Ⅰ级。结论新型复合纤维蛋白胶的磷酸钙人工骨材料具有良好的生物相容性和生物安全性。     

羟基磷灰石涂层镁铝合金的体外生物相容性研究

目的：评价羟基磷灰石（HA）涂层镁铝合金（AZ31B）的体外生物相容性。方法实验分为3组：HA涂层AZ31B浸提液组（H组）、阳性对照组（P组）和空白对照组（N组）。将L929细胞与各组混合液培养3、5和7 d,采用WST-1法检测细胞活力并进行细胞毒性分级。各组混合液与稀释兔血混匀,测定吸光度（OD）并计算溶血率。采用各组混合液对白化豚鼠分别进行皮内诱导、局部诱导和激发,观察去除贴敷片24、48、72 h动物激发部位皮肤情况。结果3、5和7dN组和H组细胞毒性反应分级为0级,P组部分细胞毒性反应分级为3级;各时间点H组、N组细胞活力均高于P组,差异有统计学意义（P ＜0.05）。H组、P组和N组OD值分别为（0.004±0.001）、（0.648±0.050）和（0.008±0.003）;H组溶血率为-0.6%,无溶血反应。去除贴敷片24、48、72 h H组皮肤无明显改变,P组可见中度至重度融合性红斑。结论体外实验提示HA涂层镁铝合金具有良好的体外生物相容性。     

明胶-白芨胶/丹参多孔材料的生物相容性

目的 观察明胶-白芨胶/丹参多孔材料的生物相容性.方法 小鼠腹腔注射材料浸提液,观察其急性毒性反应;家兔耳缘静脉注射浸提液,观察其发热反应;分光光度法分析0.02 s/ml浓度浸提液溶血率;噻唑蓝(MTr)比色法观察3种浓度(0.10、0.02、0.01 g/m1)浸提液对L929细胞生长的影响;材料植入SD大鼠皮下,分别于第1…2 4 8周取出,评价材料组织相容性.结果 浸提液腹腔注射未引起小鼠急性毒性反应;注入家兔耳缘静脉内未引起发热反应;浸提液溶血率为2.59%,符合规定;3种浓度浸提液在l d时RGR分别为102.8、101.2、100.5,3 d时RGR分别为104.5、100.6、103.4,7 d时RGR分别为109.7、104.6、106.7;材料在体内约8周完全降解,未见异常反应.结论 明胶.白芨胶/丹参多孔材料无毒性,无热源性,无溶血性及细胞毒性,具有良好的生物相容性.     

新型生物降解材料PHB细胞相容性研究

目的 本文对新研制的聚－β羟基丁酯（ＰＨＢ）这一生物可降解材料进行细胞相容性研究。方法 采用Ｌ９２９小鼠成纤维细胞，经材料高温浸提液、常温浸出液与Ｌ９２９细胞接触及直接在ＰＨＢ膜片上种植该细胞，运用四唑盐比色法（ＭＴＴａｓ－ｓａｙ）测定其１，３，５天Ｌ９２９细胞的相对增殖率及其毒性程度。结果 ＰＨＢ材料在高温及常温下物理、化学性质稳定。结论 ＰＨＢ细胞相容性好，细胞毒性程度０级。     

聚己内酯电纺纤维的制备及生物相容性研究

目的：评价聚己内酯电纺纤维的生物相容性,对其在组织工程支架方面的应用前景进行探讨。方法：采用静电纺丝法制备聚己内酯纳米纤维,场发射扫描电镜观察其表面形貌及内部结构,通过溶血实验、粘膜刺激实验和细胞毒性实验（MTT法）初步评价其生物相容性。结果：场发射扫描显微镜观察显示所获得纤维呈无纺多孔网状结构,直径范围为153～612nm,纤维形态光滑均一。溶血实验显示材料无溶血现象,不影响凝血功能;MTT试验显示L929细胞在材料浸提液种中生长良好,细胞毒性为0级;粘膜刺激实验未见异常组织学反应。结论：聚己内酯电纺纤维具有良好的生物相容性,对其在组织工程支架材料领域的应用有进一步研究的价值。     

纳米氧化锆强韧化高孔隙率磷酸钙人工骨细胞支架生物学评价

目的：对自行研制的纳米氧化锆强韧化高孔隙率磷酸钙人工成骨细胞支架[hyper-porosity Ca3(PO4)：bone cells frame／NM ZrO2 reinforced以下简称支架]的体外生物相容性进行评价。方法：采用细胞毒性试验、溶血试验和急性全身中毒试验3种方法。结果：(1)培养的L929成骨细胞经支架浸提液处理后形态良好，增值旺盛，材料毒性评级为0级；(2)溶血率为2．23％(小于5％)，符合溶血试验标准要求；(3)无急性全身中毒反应。结论：支架复合物具有良好的生物相容性。     

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.     

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.     

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.