Collagen Cross-Linking and Resorption: Effect of Glutaraldehyde Concentration

Cross-linked collagen bioprostheses usually are designed to be inert and nonresorbable, resulting in fatigue and wear failure in high-stress environments. Eventual replacement of the implant, although minimizing strength loss during resorption, would result in a graft with reparative ability. Kangaroo tail tendon (KTT) partially cross-linked with glutaraldehyde (GA) was evaluated in vitro for resistance to bacterial collagenase digestion and in vivo for biocompatibility and resorbability in an intramuscular implant assay. Cross-linking was quantified by thermal denaturation studies. Incomplete cross-linking was achieved with concentrations of GA less than 0.1% (w/v). KTT cross-linked in greater than or equal to 0.05% GA were collagenase resistant being incompletely digested after 240 h. Cross-linking of KTT with low concentrations of GA resulted in partial collagenase resistance and slowed resorption.     

Temperature Feedback and Collagen Cross-Linking in Argon Laser Vascular Welding

A preliminary single-animal study of in vivo argon laser vascular welding was conducted using a canine model. The effects of temperature feedback control and saline drip cooling on patency and collagen cross-linking were investigated. The surface temperature at the centre of the laser spot was monitored using a two-colour infrared thermometer. The surface temperature was limited by either a saline drip or feedback control of the laser. Acute patency was evaluated and collagen cross-link assays were performed. Though both protocols yielded successful tissue fusion, welds maintained at a surface temperature of 50°C using feedback control had an elevated cross-link count compared to controls, whereas tissues irradiated without feedback control experienced a cross-link decrease. Simulations using the LATIS (LAser-TISsue) computer code suggest that drip-cooled procedures achieve significantly higher temperatures beneath the tissue surface than temperature feedback-controlled procedures. Differences between the volumetric heating associated with drip-cooled and feedback-controlled protocols may account for the different effects on collagen cross-links. Covalent mechanisms may play a role in argon laser vascular fusion. Paper received 20 August 1997; accepted in final form 16 September 1997.     

The Development of Polymeric Cardiovascular Collagen Prostheses

In an attempt to develop a long-lasting, non-thrombogenic, collagen cardiovascular prosthesis this laboratory has sequentially evaluated a series of modified collagen structures treated as polymers. Bovine arteries and human umbilical cords have been subjected to various chemical modifications and grouped as follows: 1.) fresh, untreated vessels, 2.) commercially available dialdehyde starch tanned grafts, 3.) ficin digested (muscle and elastin removed) vessels, 4.) ficin digested negatively charged, untanned grafts, 5.) ficin digested, negatively charged, dialdehyde starch tanned grafts, 6.) ficin digested, oxidized carboxymethylcellulose tanned grafts, 7.) ficin digested, glutaraldehyde tanned, protein cross-linked, negatively charged grafts. The aim in each case was to create a specific recurrent stereo specific electrochemical charge at the blood-tissue interface. These tubular grafts were then evaluated in several positions following canine implantation. The results confirmed that the single most important factor in assuring long-term patency and function was provision of a uniform, highly covalently bonded, glutaraldehyde tanned, negative surface charge. Unmodified grafts thrombosed and then became calcified or dissolved within a short period of time. Techniques for evaluation included resistance to thrombosis and observed characteristics of the grafts at periodic intervals of 1 second, 2 hours, 2 weeks, 1 month, 3 months, 6 months, 9 months, 12 months and longer. Upon removal, each of these grafts was inspected, photographed, tested for tensile strength, and observed by light and scanning electron microscopy. In summary, the most satisfactory graft was the ficin digested, glutaraldehyde tanned, negatively charged prosthesis. Subsequently, these grafts were prepared for implantation in humans. At this time approximately 69 segments have been implanted in 35 patients. The majority (36) have been implanted in the femoral-popliteal position. Axillofemoral, femorofemoral, aortorenal, peripheral arteriovenous, coronary, iliopopliteal and femoroperoneal bypasses were also performed. These results have been compared with gas endarterectomy, saphenous vein bypass (conventional), and bovine heterograft prostheses in similar implantation sites. Follow-up of this group to two years reveals patency approaching that of autogenous saphenous vein grafts and surpassing that of conventional bovine heterografts. These data suggest that collagen with chemical and surface charge modification may lead to a new generation of biological cardiovascular prostheses exhibiting improved performance characteristics and freedom from thrombosis.     

胶原凝胶复合骨胶原基质(BCM)负载关节软骨细胞的实验研究

目的 探讨胶原凝胶包埋软骨细胞接种BCM支架的三维培养对软骨细胞生长及功能的影响.方法 将胶原凝胶包埋的关节软骨细胞接种BCM支架并在体外培养,应用倒置相差显微镜和扫描电镜观察软骨细胞的粘附、生长和增殖情况,培养14d,行苏木精-伊红、甲苯胺蓝染色观察软骨组织形成情况.结果 软骨细胞在支架上粘附、生长和增殖良好,体外培养14d能形成较成熟的软骨组织.结论 胶原凝胶复合BCM支架具有良好的细胞相容性,可作为负载生长因子的载体.     

Nonenzymatic Cross-Linking Pentosidine Increase in Bone Collagen and Are Associated with Disorders of Bone Mineralization in Dialysis Patients

Disorders of bone and mineral metabolism are common complications in chronic kidney disease (CKD) patients and lead to significantly increased fracture risk, morbidity, and mortality of cardiovascular disease due to ectopic calcifications, contributing to a worsening prognosis. Bone strength is determined by not only bone mineral density but also bone quality, which is dependent on bone collagen cross-links. Collagen cross-links are classified into enzymatic immature and mature types and nonenzymatic advanced glycation end products (AGEs). Pentosidine is well established as one of the AGEs that accumulates markedly in CKD patients. The chemistry, function, and clinical relevance of cross-links have been revealed, whereas bone quality and the relationship with bone mineralization in CKD patients are not clear. We performed transiliac bone biopsies on 22 dialysis patients (mean age 56 ± 9 years) with severe secondary hyperparathyroidism and measured cross-links by evaluating bone histomorphometry. Cross-links data were compared with age-matched non-CKD subjects (mean age 58 ± 8 years, n = 17). Enzymatic collagen cross-links were formed to a similar extent compared with non-CKD subjects and showed a positive correlation with plasma intact parathyroid hormone. Pentosidine was remarkably increased in dialysis patients and inversely correlated with bone-formation rate/bone volume and mineral apposition rate. This study suggests that AGE collagen cross-links strongly associate with disorders of bone metabolism in dialysis patients.     

The rotaglide total knee arthroplasty: Prosthesis Design and Early Results

The Rotaglide knee (Cozim Medical, UK) is a three-part knee containing a mobile polyethylene meniscal platform, imparting reduced loosening forces to the tibia. The femoral component design provides a high degree of congruency throughout the range of motion from 0° to 110°, and both femoral and tibial components ensure minimal bone removal. The system is versatile, including a large number of component options, and it may be used in both primary and revision arthroplasties. The first results in 170 cemented knees (161 patients) with 2- to 5-year follow-up periods (average, 3.1 years) were very encouraging (excellent or good in 95% of knees, based on the British Orthopaedic Association knee assessment system). Poor results were seen only in revision cases. There have been no mechanical implant failures and no platform bearing dislocations, and the platforms continue to move as documented by postoperative roentgenograms, which show the metal markers of the platforms moving anteriorly in flexion and posteriorly in extension.     

The Prosthesis Salvage Operation: Immediate Replacement of the Infected Penile Prosthesis

Purpose

We describe our experience with salvage of the infected penile prosthesis at initial presentation in 11 patients.

Materials and Methods

All patients with prosthesis infection who presented since 1991 were considered for salvage surgery. Contraindications to a salvage operation included necrotic infections, diabetic patients with purulence in the corporeal bodies, rapidly developing infections and erosion of the device cylinders.

Results

In 1 patient in this group a salvage attempt was repeated after re-infection, for an overall success rate of 91 percent. Mean followup for the group was 21 months (range 9 to 42). Staphylococcus epidermidis was the infecting organism in 75 percent of out patients.

Conclusions

Our experience demonstrates the safety and advantages of the immediate salvage technique.     

国人正常肱骨头形态学与假体设计的相关研究

目的测量国人肱骨头相关解剖数据,为设计适合中国人的肱骨头假体提供参考值.方法100根成对防腐肱骨(男28对,女22对),用CT软件测量头心-干轴距、头干角、头-结节高度差、头半径、关节面张角等共13项参数.结果所得数据行统计学处理,得出各参数分布规律及其间的相关性,性别间比较有显著差异,而左右间差异不显著,除头干角比西方人稍大外,其余参数均较西方人小,差异有非常显著性意义(P＜0.01).结论有必要设计符合国人肱骨解剖特点的假体.     

Modified Shoelace Dural Closure with Collagen Matrix in Extended Transsphenoidal Surgery

Extended endonasal transsphenoidal surgery (eTSS) offers a wide surgical field for various parasellar lesions; however, intraoperative high-flow cerebrospinal fluid (CSF) leakage is inevitable. Therefore, secure sellar reconstruction methods are essential to prevent postoperative CSF leakage. Although collagen matrix has been applied for dural reconstruction in neurosurgery, its suitability for application in extended eTSS remains unclear. Eighteen patients underwent modified shoelace dural closure using collagen matrix after lesionectomy via extended eTSS. In this technique, a collagen matrix, which was placed subdurally (inlay graft), was continuously sutured with both open dural edges like a shoelace. Then, another collagen matrix was placed epidurally (onlay graft), and rigid reconstruction was performed using the septal bone and a resorbable fixation mesh. Postoperative CSF leakage did not occur in 17 patients but did occur in 1 patient with tuberculum sellae meningioma. In this case, the CSF leakage point was detected just around the area between the coagulated dura and the adjacent collagen matrix. The collagen matrix harvested from this area was pathologically examined; neovascularization and fibroblastic infiltration into the collagen matrix were not detected. On the other hand, neovascularization and fibroblast infiltration into the collagen matrix were apparent on the surface of the collagen matrix harvested from the non-CSF leakage area. Our novel dural closure technique using collagen matrix could be an effective option for sellar reconstruction in extended eTSS; however, it should be applied in patients in whom normal dural edges are preserved.     

国人髌骨形态学研究及其在髌骨假体设计中的意义

目的通过研究正常国人髌骨关节面的形态学特征,探讨它们在国人髌股关节假体的髌骨假体设计中的意义。方法通过影像学方法对国人髌骨的Wiberg分型进行流行病学统计分析,并将国人统计学结果和西方人数据进行比较。结果200例国人髌骨的Wiberg分型结果为:Ⅰ型23例占11·5%,Ⅱ型占128例64%,Ⅲ型42例占21%,Ⅳ型7例占3·5%,在国人髌骨中WibergⅡ型占大多数,WibergⅠ型只占少部分。结论在国人髌股关节假体设计过程中,髌骨假体的形态以WibergⅡ型为模板采取偏心型设计更符合国人髌骨形态学特征。     

Biomechanical Evaluation of Acellular Collagen Matrix Augmented Achilles Tendon Repair in Sheep

The rate of rerupture of repaired Achilles tendon in young and athletic populations remains high despite improvement in surgical techniques, suture design, and postsurgical management. Acellular biological matrices can be used to enhance the immediate strength of repaired tendons and to serve as scaffolds for cell in-growth and constructive tissue remodeling. A number of commercially available matrices have been used clinically, albeit with varying degrees of success and failure. The disparity is likely attributable to the different physical and biochemical properties of individual matrices. In this study, we investigated the biomechanical characteristics of 2 different acellular collagen matrices, namely TissueMend^® and GraftJacket^®, using a sheep Achilles tendon repair model. Static and cyclic creep, cyclic and linear construct stiffness, maximum load to failure, and displacement at maximum load were determined at time zero. We found that the maximum load to failure, displacement, and ultimate failure mode were similar between tendons augmented with either acellular collagen matrix; however, TissueMend augmentation yielded lower creep and smaller construct elongation than did GraftJacket. The results indicated that the strength of TissueMend-augmented tendons and GraftJacket-augmented tendons was not statistically significantly different, although tendons augmented with TissueMend displayed greater stiffness, which may be clinically advantageous in the restoration of ruptured tendons.     

人皮质骨矿化基质中骨盐框架结构

目的：研究人皮质骨矿化基质中骨盐的框架结构及框架中骨微间隙。方法：应用透射电镜、场发射扫描电镜观察、电脑图像分析及能谱分析，分析无骨病成人长骨、扁骨２００例骨盐分布特征。结果：骨盐框架结构由微柱、微梁、微小梁、弓状梁、致密点、隔板和骨微间隙构成。骨微间隙由洞、内衬和壁组成，洞平均直径为８４．４±７５．６ｎｍ，与骨小管相比有显著差异（Ｐ值＜０．００１），平均密度为１１～１７个／μｍ２，与骨小管之比超过１０：１。骨盐分针形结晶和微颗粒结晶。结论：骨盐框架结构及骨微间隙是骨盐在人皮质骨矿化基质中的存在形式，可能与骨盐吸收、沉着有关。     

等离子喷涂羟基磷灰石涂层人工股骨柄的研制

目的 :研制新型羟基磷灰石涂层人工关节。方法 :采用等离子喷涂及外送粉装置对人工股骨柄进行全柄喷涂。运用X线衍射仪、X线表面能谱仪、红外线光谱仪、扫描电镜及力学实验对涂层进行分析。结果 :涂层成分主要为羟基磷灰石 ,基本上未发生热分解 ,涂层与金属基体之间的平均结合强度为 2 9 71MPa。结论 :国产等离子喷涂羟基磷灰石涂层基本保持了羟基磷灰石材料的特性 ,结合强度能够满足关节假体的需要。     

Prosthesis of the testis in monorchism and anorchism

The authors describe the method for prosthetics of the testes in mon- and anorchism, by which the operations were carried out on 12 patients whose ages ranged from 14 to 22 years. Dow Corning (USA) prostheses were used in 3 cases, Soviet--made endoprostheses designed at the Scientific Research Institute of Rubber and Latex Articles, USSR, jointly with the Vishnevsky Institute of Surgery were applied in 9 cases. There were no postoperative complications. The late-term results were studied in follow-up periods of 1 to 4 years and proved to be satisfactory. The method deserves to be introduced into the practice of plastic surgery.     

Effects of Interleukin-1 Receptor Antagonist on Collagen and Matrix Metalloproteinases in Stress-shielded Achilles Tendons of Rats

Based on previous studies showing that interleukin-1 (IL-1) significantly increased after stress shielding, this article reports further research into the possible therapeutic applications of IL-1 receptor antagonist (IL-1Ra).Forty rats whose left Achilles tendons were denervated and completely stress shielded were divided into 5 groups: 2-week phosphate-buffered saline (PBS); 4-week PBS; 2-week IL-1Ra; 4-week IL-1Ra; and normal control. The Achilles tendons were tested morphologically, and the changes in collagen I and III, matrix metalloproteinases (MMP)-1 and -3, and tissue inhibitors of metalloproteinase (TIMP)-1 were determined. The collagen fibrils in the IL-1Ra groups were morphologically more similar to those in the control group than to those in the PBS groups. The collagen I levels increased in the 2-week groups. Significant differences existed between the PBS and IL-1Ra groups at 4 weeks. The MMP-1 level increased dramatically after stress shielding and increased less in the 2-week IL-1Ra group than in the 2-week PBS group. The degree of decrease of MMP-3 in the IL-1Ra groups was significantly less than that in the PBS groups. The collagen III and TIMP-1 levels continued to increase, and no difference was found between the PBS and IL-1Ra groups. Interleukin-1 receptor antagonist prevented morphological deterioration and collagen metabolism of the denervated Achilles tendons after stress shielding, likely by inhibiting the decline of MMP-3 and increasing MMP-1 levels at an early stage.     

An Intrapleural Lung Prosthesis: Rationale, Design, and Testing

Abstract: Extracorporeal life support (ECLS or ECMO) is standard treatment for severe respiratory failure but poses many contraindications to future lung transplantation. The solution to this dilemma is the implantable gas exchange device (IGED) or artificial lung. Preliminary efforts to create such an artificial lung have been made since 1970 and include designs involving single devices, intravascular devices (i. e., IVOX), and combination heart–lung devices, Stringent requirements govern the design of such a device, the most important of which are high gas exchange efficiency, low resistance to blood flow, and size. This paper describes such a device. It incorporates large diameter inflow and outflow ports in close proximity and a low resistance wound hollow fiber core encapsulated in a compliant outer shell which conserves the work of the right ventricle. In a large animal model (adult sheep) this device was connected in line with the main pulmonary artery in series with the native lungs. This configuration has the advantages of using the lungs as an embolic filter, perfusing the lungs with fully oxygenated blood, and maintaining the integrity of the anatomy necessary for transplant. Laboratory experiments have run >8 h. Preliminary data show that the animals have remained hemodynamically stable while the devices have supported the animals completely by supplying 100% O₂ saturation with PO₂ values ranging from 250–350 mm Hg. Additionally, this model makes possible the study of respiratory failure without introducing other variables such as extracorporeal circuits or pumps. The other metabolic, endocrine, and reticuloendothelial functions of normal and injured lungs can now be studied more precisely by excluding these variables. Further studies are needed to evaluate this device in chronic (long–term implantation) experiments before clinical application.