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。     

Reduction of Plasma Fibrinogen, Immunoglobulin G, and Immunoglobulin M Concentrations by Immunoadsorption Therapy with Tryptophan and Phenylalanine Adsorbents

Abstract Immunoadsorption (1A) therapy with tryptophan (TR-350) or phenylalanine (PH-350) adsorbents has been used to reduce the concentration of serum antibodies in human lymphocyte antigen (HLA)-immunized patients. Other forms of plasma purification have been reported to reduce the level of fibrinogen, which affects the blood properties. In this study we investigated the effects of IA therapy using both adsorbents on plasma fibrinogen and immunoglobulins G and M in 13 patients (8 patients were treated with TR-350, and 5 patients were treated with PH-350). During each session 1 plasma volume (2.8 ± 0.4 L of plasma) was processed through the immunocolumn and then returned to the patient together with the blood cells. Compared with the pretreatment values, the plasma fibrinogen, IgG, and IgM concentrations were significantly reduced after IA therapy (p < 0.01 for TR-350; p < 0.04 for PH-350). There was a positive correlation between the degree of reduction of plasma proteins and the number of IA treatments given. A nonpara-metric test (Wilcoxon's signed-rank test or the Mann-Whitney test) was used for statistical analysis. We conclude from our study that IA therapy effectively lowers the plasma levels of fibrinogen, IgG, and IgM and thus can be considered a valuable alternative to other blood purification methods.     

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.     

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.     

The analgesic effect of racemic ketamine in patients with chronic ischemic pain due to lower extremity arteriosclerosis obliterans

Background : Ketamine in sub-dissociative doses has been shown to have analgesic and phantom-Limb pain, where conventional treatment has often failed. Chronic ischemic pain due to lower extremity arteriosclerosis obliterans often responds poorly to analgesics, and the pain-generating mechanisms are not well understood.
Methods : Eight patients with rest pain in the lower extremity due to arteriosclerosis obliterans were given sub-dissociative doses of 0.15, 0.30, or 0.45 mg/kg racemic ketamine and morphine 10 mg as a 5-min infusion on four separate days in a cross-over, double-blind, randomised protocol. Plasma levels of (S)- and (R)-ketamine and their nor-metabolites were analysed with an enantioselective high-performance liquid chromatography (HPLC) method. Pain levels were evaluated with a visual analogue scale (VAS).
Results : Individual pain levels were highly variable during and after all the infusions but the pooled pain levels showed a dose-dependent analgesic effect of ketamine with a transient but complete pain relief in all patients at the highest dose (0.45 mg/ kg). Side-effects, mainly disturbed cognition and perception, were pronounced and dose-dependent. Morphine 10 mg had an analgesic peak at 20 min and 5/8 patients had complete pain relief. The remaining 3 patients also had high baseline pain scores, indicating a higher analgesic potency for the 0.30 and 0.45 mg/ kg ketamine doses than for morphine 10 mg.
Conclusion : We have demonstrated a potent dose-dependent analgesic effect of racemic ketamine in clinical ischemic pain. Due to a narrow therapeutic window, this analgesic effect is probably best utilised in combination with other analgesics.     

Intravenous endotoxin does not increase tissue extravasation of albumin in rats

Background : It is unclear whether activation of the inducible nitric oxide synthase (iNOS) increases or decreases the extravasation of plasma.
Methods : Chloralose anaesthetised male Wistar rats received E. coli lipopolysacharide (LPS), 3 mg kg^-1 i.v., or the corresponding volume of saline, 3 or 5 h before the end of the experiment. Mean arterial pressure (MAP) and heart rate (HR) were recorded. Tissue clearance of radio-labelled albumin, during the last 2 h of each experiment, was determined by a double-isotope method. In separate animals, the serum concentration of nitrite and nitrate was determined, 5 h after LPS or the solvent.
Main Results : LPS initially decreased MAP and lastingly increased HR. In the 3-h LPS animals (n=8), tissue plasma clearance was lower in the heart and calf muscle and increased only in diaphragm, compared to corresponding control animals (n=8). In the 5-h LPS rats, clearance was lowered (n=8) in the entire gastrointestinal tract and in testes, compared to controls (n=8). The serum nitrite/nitrate concentration was higher in animals given LPS (n=6) than in controls (n=6).
Conclusion : After LPS, tissue clearance of albumin was not increased in any major tissue, in spite of increased serum levels of NO end products. Apparently, after activation of iNOS, the augmented release of NO is not necessarily associated with increased albumin extravasation.     

The multiply injured child

Blunt trauma is the principal cause of childhood death in many developed countries. This review outlines the differences between adults and children with respect to resuscitation and treatment of orthopaedic injuries in a child with polytrauma. Recent advances in techniques of fracture stabilization are reported.     

Adrenaline markedly improves thoracic epidural analgesia produced by a low-dose infusion of bupivacaine, fentanyl and adrenaline after major surgery: A randomised, double-blind, cross-over study with and without adrenaline

Background: Basic pharmacological research indicates that there are synergistic antinociceptive effects at the spinal cord level between adrenaline, fentanyl and bupivacaine. Our clinical experience with such a mixture in a thoracic epidural infusion after major surgery confirms this. The objectives of the present study were to evaluate the effects on postoperative pain intensity, pain relief and side effects when removing adrenaline from this triple epidural mixture. Methods: A prospective, randomised, double-blind, cross-over study was carried out in 24 patients after major thoracic or abdominal surgery. Patients with only mild pain when coughing during a titrated thoracic epidural infusion of about 10 ml · h^?1 of bupivacaine 1 mg · ml^?1, fentanyl 2 μg · ml^?1, and adrenaline 2 μg · ml^?1 were included. On the 1^st and 2^nd postoperative days each patient was given a double-blind epidural infusion, at the same rate, with or without adrenaline. The effect was observed for 4 h or until pain when coughing became unacceptable in spite of a rescue analgesic procedure. Rescue analgesia consisted of up to two epidural bolus injections per hour and i.v. morphine if necessary. All patients received rectal paracetamol 1 g, every 8 h. Fentanyl serum concentrations were measured with a radioimmunoassay technique at the start and end of each study period. Main outcome measures were extent of sensory blockade and pain intensity at rest and when coughing, evaluated by a visual analogue scale, a verbal categorical rating scale, the Prince Henry Hospital pain score, and an overall quality of pain relief score. Results: The number of hypaesthetic dermatomal segments decreased (P <0.001) and pain intensity at rest and when coughing increased (P <0.001) when adrenaline was omitted from the triple epidural mixture. This change started within the first hour after removing adrenaline. After 3 h pain intensity when coughing had increased to unacceptable levels in spite of rescue analgesia (epidural bolus injections and i.v. morphine). Within 15–20 min after restarting the triple epidural mixture with adrenaline, pain intensity was again reduced to mild pain when coughing. Serum concentration of fentanyl doubled from 0.22 to 0.45 ng · ml^?1 (P <0.01), and there was more sedation during the period without adrenaline. Conclusions: Adrenaline increases sensory block and improves the pain-relieving effect of a mixture of bupivacaine and fentanyl infused epidurally at a thoracic level after major thoracic or abdominal surgery. Serum fentanyl concentrations doubled and sedation increased when adrenaline was removed from the epidural infusion, indicating more rapid vascular absorption and systemic effects of fentanyl.     

Utilisation des médicaments prokinétiques en réanimation : indications et limites ?

Enteral feeding is often limited by gastric and intestinal motility disturbances in critically ill patients, particularly in patients with shock. So, promotility agents are frequently used to improve tolerance to enteral nutrition. This review summaries the pathophysiology, presents the available pharmacological strategies, the clinical data, the counter-indications and the principal limits. The clinical data are poor. No study demonstrates a positive effect on clinical outcomes. Metoclopramide and erythromycin seems to be the more effective. Considering the risk of antibiotic resistance, the first line use of erythromycin should be avoided in favor of metoclopramide.