犬骨形态发生蛋白/羟基磷灰石梯度涂层骨的结合性能

目的探讨复合重组人骨形态发生蛋白(rhBMP)的羟基磷灰石(HA)梯度涂层植入体的界面骨结合性能。方法6只健康成年杂交犬股骨内、外髁关节面各垂直植入1个种植体,共植入钛合金圆柱体(Ti组)、HA涂层钛合金圆柱体(HA组)、复合rhBMP的HA涂层钛合金圆柱体(BMP组)各8个。12周时取材进行界面组织学观察、顶出试验和扫描电镜检查。结果界面组织学和扫描电镜观察显示HA组和BMP组界面骨结合良好。Ti组、HA组和BMP组骨结合率分别为(11.53±10.79)%、(81.51±4.53)%、(92.71±5.30)%(P<0.01);抗剪切力强度分别为(2.36±1.04)、(21.65±1.48)、(30.95±3.67)Mpa(P<0.01)。结论复合BMP的HA梯度涂层在负重情况下界面骨结合好,结合强度高,已具备应用于新型涂层假体研制的生物学性能。     

HA梯度涂层复合BMP人工股骨柄的研究

目的研究新型HA梯度涂层人工股骨柄假体及其复合重组人骨形态发生蛋白-2(rhBMP-2)后的界面生物学特征。方法将15只健康成年杂交犬随机分成三组,行右侧人工股骨头置换,分别植入钛合金人工股骨柄(Ti组)、HA涂层钛合金人工股骨柄(HA组)和复合rhBMP-2的HA涂层钛合金人工股骨柄(BMP-HA组),12周后处死动物,取有植入假体的股骨上段进行X线检查和界面组织学观察,处死前肌内注射盐酸四环素行荧光标记。结果X线检查显示Ti组中有1例假体周围出现局部透亮带。HA组及BMP-HA组股骨柄假体周围可见新骨形成。光镜下新型HA梯度涂层无明显降解和碎裂,性质稳定。Ti组、HA组和BMP-HA组界面骨结合率分别为4.05%±7.66%、71.04%±9.81%和88.86%±6.56%。显示HA组和BMP-HA组界面骨结合良好,骨结合率显著高于Ti组(P<0.01),BMP-HA组界面骨结合率也显著高于HA组(P<0.01)。BMP-HA组的界面有较强的四环素荧光标记,显示界面成骨活跃。结论新型HA梯度涂层假体可引导骨组织长入涂层,与骨组织结合良好,结合率高,能增加假体的稳定性。该涂层可复合rhBMP-2发挥协同作用,明显增加涂层假体的骨整合,有望成为可供临床使用的新型涂层假体。     

双梯度羟基磷灰石涂层复合转化生长因子的研究

目的　探讨双梯度羟基磷灰石涂层假体材料的生物学特性 ;检测转化生长因子对羟基磷灰石 (HA)涂层与骨界面之间生物连接的影响。方法　将钛合金植入体 (Ti)、带羟基磷灰石涂层的钛合金植入体 (HaTi)和TGF β复合涂层植入体 (TGFHaTi)植入犬股骨 ,术后 3、6、16周分别处死 3组动物 ,通过组织切片、计算机图像分析、顶出试验、扫描电镜等方法进行观察。结果　早期骨 假体界面骨性结合率比较 :Ti 相似文献   

金属与羟基磷灰石微孔表面股骨植入体与骨结合强度的比较研究

目的比较金属与羟基磷灰石(hydroxyapatite,HA)微孔表面股骨植入体与骨的结合强度.方法用等离子喷涂技术,分别喷涂HA微粒和钴铬钼合金微粒于不锈钢三棱针表面,配对植入15只成年家兔的股骨,饲养2个月作拔出试验,并比较手术当日与2个月后的X线改变.结果HA与钴铬钼合金涂层三棱针平均剪切强度分别为(0.98±0.12)MPa和(0.65±0.15)MPa,二者有显著性差异(P＜0.05).X线片HA涂层三棱针周围有较多的成骨反应,透明区较金属涂层三棱针要少而窄.结论植入兔的股骨短时间内,HA微孔表面植入体较金属微孔表面植入体更为稳定.     

纳米级羟基磷灰石梯度涂层植入体骨结合的研究

目的评价纳米级羟基磷灰石梯度涂层(HAP)植入体-骨界面骨结合情况。方法在Beagle犬股骨内植入纳米级HAP梯度涂层栓、普通级HAP涂层栓和钛合金(Ti-6AL-4V)栓,在4、8、12周比较X线结果和植入体-骨界面剪切强度。结果各时间点纳米级HAP涂层组和普通HAP梯度涂层组的X线结果相当,植入体-骨界面剪切强度均优于钛合金组和钛合金组。结论纳米级HAP梯度涂层植入体与骨有很好的结合力,能够加速骨质的愈合。     

双梯度羟基磷灰石涂层复合rhBMP-2研究

目的 :检验双梯度生物活性涂层假体材料的生物学特性 ;检测rhBMP 2对HA涂层与骨界面之间生物连接的影响。方法 :将同一规格的 3种不同植入体 (Ti、Hati、rhBmp 2HaTi)植入狗股骨 ,术后 3、6、16周分别处死三组动物 ,通过X线照片、不脱钙带植入体的组织切片、计算机图像分析、顶出试验、扫描电镜等检查手段进行观察。结果 :早期骨 -假体界面骨性结合率比较 :Ti 相似文献   

羟基磷灰石梯度涂层的生物学研究

目的：本实验研究HA梯度涂层材料在体内负重条件下的生物学表现,方法：将经梯度涂层羟基磷灰石的钛合金栓与非涂层钛合金栓分别植入狗下肢的负重区,观察植入体与骨结合界面的生物学特性,结果：组织学研究显示类骨样基质直接沉积在HA涂层表面,涂层与宿主骨紧密结合。而非涂层组新生骨形成的数量和速度远低于HA涂层组,生物力学测试显示HA组与宿主骨结合界面的抗剪强度均远大于非涂层组（P＜0．01）,结论：结果表明HA梯度涂层法作为新颖的层方法有其实际临床应用价值。     

微孔涂层植入物与骨组织界面骨小梁的疲劳微观损伤

目的　探讨微孔涂层植入物界面骨小梁的疲劳微观损伤规律。方法　将钛合金微孔涂层试件植入犬股骨大粗隆 ,6月后材取 ,分别行静态拉伸剪切试验测定界面静态剪切应力强度极限 ,用配置疲劳台的扫描电镜动态观察在周期交变载荷下 ,界面骨小梁的疲劳损伤规律。结果　微孔涂层植入物界面静态剪切应力强度极限为 4 2 6 1± 0 372Mpa。骨小梁疲劳损伤规律表现为早期微孔内骨小梁的板层骨变形和裂纹形成 ,中期的应力转移 ,界面外 1mm处的骨小梁损伤 ,晚期的微孔内、外骨小梁碎化 ,胶原纤维脱粘、断裂。结论　 6月后微孔涂层生物学固定界面结合牢固 ,界面强度高。疲劳损伤的应力转移现象 ,为损伤修复提供了机会。     

等离子喷涂纳米氧化钛涂层骨界面剪切强度的研究

目的对等离子喷涂纳米氧化钛涂层骨界面进行生物力学性能评价。方法将钛金属基等离子喷涂纳米氧化钛涂层材料植入兔股骨髁，以无涂层钛金属作为对照。分别在植入4周、8周、12周、24周对2组进行推出实验，测定骨．涂层界面剪切强度。结果纳米氧化钛涂层组在8周、12周、24周剪切强度值均大于对照组，差异有统计学意义（P〈0．05）。剪切强度至12周达到最大值。结论中长期纳米氧化钛涂层的界面剪切强度大于无涂层对照组，体内植入纳米氧化钛涂层具有中长期的力学稳定性。     

钛铌涂层镍钛记忆合金的骨组织生物相容性

目的对镍钛(NiTi)记忆合金植入物进行表面修饰是屏蔽Ni离子释放的有效方法 ,钛铌(TiNb)合金作为涂层材料不会影响NiTi的超弹性和记忆效应。对TiNb涂层的NiTi记忆合金植入体植入骨组织后的骨组织生物相容性进行评价,为临床应用提供实验依据。方法对直径4mm、长12mm的NiTi记忆合金圆柱体采用磁控溅射技术分别进行Ti涂层和TiNb涂层,另一组仅表面抛光清洗不进行涂层。取成年杂种犬15只,体重(15±2)kg,随机分为3组,每组5只,分别为NiTi组、Ti涂层组和TiNb涂层组。制备犬双侧股骨干假体植入模型,垂直股骨外侧皮质分别植入NiTi无涂层、Ti涂层和TiNb涂层记忆合金圆柱体,每只犬植入10枚,间距1.0～1.5cm。术后12个月处死动物取材,X线片观察植入体植入方向,未与股骨皮质垂直的植入体标本作为无效标本放弃,其余有效标本一部分(NiTi组、Ti涂层组和TiNb涂层组标本数分别为12、10和14枚)进行生物力学推出实验,计算最大剪切强度;另一部分(NiTi组、Ti涂层组和TiNb涂层组标本数分别为8、5和10枚)行不脱钙切片用于组织学观察和计算骨性结合率。结果 Ti涂层组和TiNb涂层组的剪切强度分别为(95.10±10.03)、(91.20±15.42)MPa,明显高于NiTi组的(71.60±14.24)MPa(P0.01);2个涂层组间比较差异无统计学意义(P0.05)。Giemsa染色示3组植入体周围均未见明显巨噬细胞和中性粒细胞浸润,偶尔可见少量淋巴细胞。NiTi组、Ti涂层组和TiNb涂层组的骨性结合率分别为21.30%±0.23%、32.50%±0.31%和38.60%±0.58%,3组间比较差异均有统计学意义(P0.01)。结论各植入体和骨组织均具有良好的生物相容性;Ti涂层和TiNb涂层的骨生物相容性相近,但从骨性结合率结果分析,TiNb涂层的骨组织生物相容性更佳。     

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.