胶原蛋白水凝胶在软骨组织工程中的应用

由创伤或骨病所致的关节骨软骨损伤在临床中十分常见,其中软骨缺损者达40.31%。由于关节软骨自身修复能力低下,采用组织工程技术对关节软骨损伤进行修复是目前采用再生医学治疗关节软骨损伤的新方法。组织工程支架按照性状可分为预成型支架材料及水凝胶材料两大类。传统的预成型支架材料移植技术容易给缺损周边软骨带来继发损伤,也存在支架与缺损整合不紧密等问题。如何在避免二次损伤的基础上,应用理想的仿生材料复合种子细胞修复关节不规则软骨损伤将成为未来软骨损伤修复的主要问题。选取微创、仿生并且可以原位塑形的胶原蛋白水凝胶复合种子细胞修复关节软骨损伤为损伤关节软骨的修复带来了希望。本文结合国内外相关文献对目前胶原蛋白水凝胶在软骨组织工程中的应用做一综述。     

关节软骨组织工程研究进展

组织工程技术为损伤关节软骨的修复提供了全新的治疗方法。本文就关节软骨组织工程的种子细胞、生长因子、细胞外基质支架及修复关节软骨缺损的研究进展作一综述。     

骨髓间充质干细胞修复关节软骨缺损研究进展

关节软骨损伤在临床上很常见．由于关节软骨的自身修复能力很差．关节软骨一一旦损伤即很难修复．继而会发生不可逆的病理变化，造成关节的退行性改变．严重影响患者的生活质量。目前．关节软骨损伤临床上尚无有效的治疗方法。近年发展起来的一门新兴学科一组织工程学．通过利用少量的种子细胞经过体外培养扩增，并附着在一定的吏架材料上，移植到体内而形成新的有生命力的组织。骨髓闸充质干细胞（Bone Marrow—derived Mesenchymal Stem Cells，BMSOs）用作种子细胞具有增殖能力强．多向分化潜能（可以分化为骨、软骨、肌肉、脂肪等多种组织），而且具有采集方便、对机体损伤小的特点．是软骨组织工程理想的种子细胞。     

基因强化软骨组织工程的研究进展

关节软骨的损伤修复一直是矫形外科的一个棘手问题,基因强化组织工程为关节软骨损伤的修复提供了良好的方法,组织工程包含了三要素:即种子细胞、信号因子(细胞因子或生长因子)和基质材料。本文重点综述信号因子(细胞因子或生长因子)转染种子细胞的研究。     

自体骨膜移植治疗关节软骨损伤的研究现状

关节软骨损伤修复大致分两类，即内源性修复和外源性修复。内源性修复也称骨髓刺激术，外源性修复包括生物移植和组织工程化关节软骨，前者包括骨膜、软骨膜移植，软骨细胞移植和骨-软骨移植；后者是体外构建种子细胞-载体复合物注入缺损区或者利用种子细胞悬液注入缺损区再用骨膜或软骨膜覆盖封闭软骨缺损的开口。两者均涉及到骨膜的成软骨作用。骨膜移植应用于临床治疗软骨损伤已有近20a历史，它有取材方便、对机体损害小等特点，但存在许多影响因素，限制了它的应用。本文就骨膜移植治疗关节软骨损伤的现状作一综述。     

组织工程修复重建感染关节软骨损伤的研究进展

目的综述感染关节的软骨损伤通过组织工程修复重建的研究进展。方法查阅组织工程修复感染关节的软骨损伤相关的国内外文献并回顾分析,综述修复软骨损伤的支架材料与种子细胞的选择和诱导及感染关节的抗生素遴选,评估组织工程修复感染关节的软骨损伤的可行性。结果藻酸盐是良好的细胞培养支架材料;高糖培养条件、胰岛素、地塞米松、转化生长因子B1（TGF-131）能诱导骨髓间充质干细胞（BMSCs）向软骨细胞分化;庆大霉素联合局部缓释可用于治疗关节感染。结论BMSCs种植于庆大霉素一藻酸盐缓释系统内并植入感染关节软骨缺损处可成为治疗感染关节软骨损伤的一种新思路。     

关节软骨组织工程研究进展

组织工程技术为损伤关节软骨的修复提供了全新的治疗方法。本文就关节软骨组织工程的种子细胞、生长因子、细胞外基质支架及修复关节软骨缺损的研究进展作一综述。1　概述关节软骨损伤后自身修复能力有限,即使在持续被动活动下,直径超过2～4mm的软骨缺损也很难愈合。成熟关节软骨无血液供应、神经支配和淋巴回流,因此,未达到软骨下骨的软骨内损伤几乎不能愈合,仅在伤口周围产生短暂的软骨细胞增殖和合成少量基质,逐渐引起关节表面退变,在一定条件下,滑膜细胞也有利于软骨修复。而穿过有血液循环的软骨下骨的全厚软骨损伤,在某些情况下可发生…     

组织工程化软骨修复关节软骨损伤研究进展

关节软骨自身修复能力差,其损伤后的有效治疗成为临床难题。软骨组织工程中种子细胞、支架及生物活性因子是目前研究的热点。体内软骨生长的微环境中含有多种生物活性因子,各因子间相互影响构成纵横交错的关系网。然而,外源性因子半衰期短,易降解,很难达到修复损伤软骨需要的浓度。转基因技术在组织工程中的应用实现了外源性生物活性因子在局部持续并高效的表达,促进了损伤软骨修复。该文就组织工程化软骨修复关节软骨损伤研究进展作一综述。     

软骨组织工程与细胞黏附关系研究进展

关节软骨是一种无血管组织，损伤后自身愈合能力非常有限，关节软骨缺损的治疗已成为困扰临床医生的一个难题。随着生命科学和工程学的发展，使用组织工程技术构建关节软骨的替代品修复关节软骨损伤已经成为研究热点，目前在临床应用亦已获得成功。组织工程细胞．支架材料之间的紧密黏附反应对细胞的增值、表型的表达、细胞外基质的合成具有重要的作用，但由于种子细胞和载体支架之间的黏附力不强，种子细胞容易从支架上脱落，[第一段]     

关节软骨损伤修复基础研究进展

关节软骨损伤修复基础研究进展杨贵勇，卢世壁关节软骨损伤是临床骨科常见疾病。由于关节软骨是无血管、淋巴管和神经的组织，自身修复能力有限，损伤后常导致关节功能活动障碍。如果有修复，其修复组织的组成、结构和力学特性均明显区别于正常关节软骨。为此，国内外有关...     

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.     

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.     

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.     

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.     

Anesthésie générale chez l’enfant : quid des pratiques en 2010 ?

Introduction

The practice of pediatric anesthesia requires a regular update of scientific knowledge and technical skills. To provide the most adequate Continuing Medical Education programs, it is necessary to assess the practices of pediatric anesthesiologists. Thus, the objective of this survey was to draw a picture of the current clinical practices of general anesthesia in children, in France.

Material and methods

One thousand one hundred and fifty questionnaires were given to anesthesiologists involved in pediatric cases. These questionnaires collected information on various aspects of clinical practice relative to induction, maintenance, recovery from general anaesthesia and also classical debated points such as children with Upper Respiratory Infection (URI), emergence agitation, epileptoid signs or anaesthetic management of adenoidectomy. Differences in practices between CHG (general hospital), CHU (teaching hospital), LIBERAL (private) and PSPH (semi-private) hospitals were investigated.

Results

There were 1025 questionnaires completed. Fifty-five percent of responders worked in public hospitals (CHG and CHU); 77% had a practice that was 25% or less of pediatric cases. In children from 3 to 10 years: 72% of respondents used always premedication and two thirds performed inhalation induction in more than 50% of cases. For induction, 53% used sevoflurane (SEVO) at 7 or 8%. Respondents from LIBERAL used higher SEVO concentrations. Tracheal intubation was performed with SEVO alone (37%), SEVO and propofol (55%) and SEVO with myorelaxant (8%), 93% of respondents used a bolus of opioid. For maintenance, the majority of respondents used SEVO associated with sufentanil; desflurane and remifentanil were more frequently used in CHU. Two thirds of respondents used N₂O. Depth of anesthesia was commonly assessed by hemodynamic changes (52%), end tidal concentration of halogenated (38%) or automated devices based on EEG (7%). In children with URI, 98% of respondents used SEVO for anesthesia. To control the airway 42% used a tracheal tube, 30% a laryngeal mask and 20% a facial mask. Emergence agitation was an important concern for two thirds of respondents, while epileptoid signs were considered as important by only 20%. Eighty-nine percent of respondents practiced anesthesia for adenoidectomy. Anesthesia was induced by inhalation of SEVO 7–8% (41%), 6% (39%) or 4% (12%), 66% put an intravenous line (less frequently in LIBERAL). 67% of the responders managed adenoidectomy without any device to control the airway (more frequently in LIBERAL), 32% administrated a bolus of opioid (less frequently in LIBERAL).

Discussion

This survey demonstrated that the practices regarding general anesthesia in children are relatively homogenous. Most of the differences appeared between LIBERAL and the others structures; the anaesthetic management for adenoidectomy illustrates these findings.     

Intérêt d’une rééducation précoce pour les patients neurologiques

Rehabilitation improves the functional prognosis of patients after a neurologic lesion, and tendency is to begin rehabilitation as soon as possible. This review focuses on the interest and the feasibility of very early rehabilitation, initiated from critical care units. It is necessary to precisely assess patients’ impairments and disabilities in order to define rehabilitation objectives. Valid and simple tools must support this evaluation. Rehabilitation will be directed to preventing decubitus complications and active rehabilitation. The sooner rehabilitation is started; the better functional prognosis seems to be.