Histological and biochemical analysis of the fibrous tissue induced by implantation of synthetic ligament (Dacron): An experimental study in a rat model

We conducted a comparative study to evaluate the quality and true nature of the fibrous tissue formed around synthetic grafts when used in ligament replacement. In one group of Lewis rats, a patellar ligament was replaced with a Dacron prosthesis; the comparison group received a tail tendon isograft. Two-, 4-, 8-, 12-, and 24-week comparisons showed histological and biochemical changes in the Dacron group alone that were consistent with foreign-body reaction. Specifically, the Dacron group showed infiltration by large numbers of macrophages and foreign-body, multinucleated giant cells. In addition, the capsule of fibrous tissue that developed around the Dacron ligaments was characterized by lower collagen solubility, a higher content of noncollagenous protein, and a higher proportion of type III collagen than that comprising the isografted tendons. The results of this study call into question the suitability of synthetics for ligament replacement.     

Effects of external beam radiation in the rat tibial nerve after crush, transection and repair, or nerve isograft paradigms

INTRODUCTION: In head and neck surgery, radiation therapy is often administered to an injured nerve. Previous studies have examined the effects of either preoperative or postoperative radiation on nerve regeneration in rodents. In these studies, histomorphometric analysis was performed up to 8 month postoperatively. Given the exceptional neuroregenerative capacity of rodents, significant differences in nerve regeneration may go undetected if nerves are evaluated at such distant postoperative time points. This study is designed with a more appropriate model and investigates the effects of radiation after three common nerve injury paradigms. METHODS: Sixty-four Lewis rates were randomized to 8 groups corresponding to uninjured, tibial nerve crush, transection and repair, or reconstruction with isografts. Half of the animals in each of these paradigms (n = 8 per group) were treated with 10 Gy of external beam radiation to the site of nerve injury at 7 days postoperatively. On postoperative day 28, functional recovery and histomorphometric assessment was performed. RESULTS: For a given paradigm of nerve injury, no significant differences in nerve fiber number, neural density, neural debris, or fiber width were noted between the control and radiated groups, and radiation did not affect functional recovery. CONCLUSION: Radiation had no discernible effect on nerve regeneration or functional recovery in the rodent nerve injury models studied. All assessments were made at time points suitable for detecting differences in nerve regeneration between groups. These findings suggest that administration of radiation to fields containing injured peripheral nerve is unlikely to adversely affect functional outcomes.     

DA与Lewis大鼠品系组合建立大鼠肝移植排斥与耐受模型

目的 建立大鼠原位肝脏移植急性排斥与自然耐受模型.方法 采用近交系雄性DA大鼠与Lewis大鼠互为供受体,改良"二袖套"法建立大鼠原位肝脏移植(rat orthotopic liver trans-plantation,ROLT)模型84例.实验分为4组:排斥组(DA→Lewis,n=12),FK506处理排斥组[DA→Lewis,n=24,术后1～7 d用FK506 0.2 mg/(kg·d)灌胃],耐受组(Lewis→DA,n=24),同基因组(DA→DA,n=24).各组中随机取6例观察生存期,其余分别于术后7、14、28 d处死6例,收集外周血及肝脏标本.检测血清标本天冬氨酸转氨酶(aspartate aminotransferase,AST)、总胆红素(total bilirubin,TBIL)浓度,病理学检查移植物排斥反应程度.结果 排斥组中位生存时间(median surviv-al time,MST)为12 d,而FK506处理排斥组MST为76 d,较排斥组明显延长(vs排斥组,P<0.01).耐受组与同基因组的MST均>120 d.术后7 d,排斥组血清AST、BILI浓度均明显高于其余3组(P<0.05);术后14 d,FK506处理组、耐受组和同基因组血清AST、TBIL浓度无明显差异.术后28 d,FK506处理组血清AST、TBIL浓度较耐受组和同基因组明显升高(P相似文献   

Carcinogenicity of 1,2-DimethyIhydrazine in Colorectal Tissue Heterotopically Transplanted into the Glandular Stomach of Rats

The present study was designed to examine the effect of the intestinal carcinogen 1,2-dimethyl-hydrazine (DMH) on grafted colorectal mucosa implanted into the glandular stomach of rats. Four groups were studied: Group 1 received the operation and DMH, Group 2 received the operation alone, Group 3 received DMH alone and Group 4 (controls) received only a sham operation. For Groups 1 and 2, about 8-mm diameter segments of colorectal tissue obtained from various sites in the large intestine of 8-week-old male F344 rats were isologously implanted into the fundic region of the stomachs of age-matched rats. DMH was injected at a dose of 20 mg/kg body weight i.m. per week for 20 weeks beginning 4 weeks after the operation. The animals were then observed for 8 months after the initial DMH treatment. In Group 1, adenocarcinomas developed in 41 of 60 successful implants (68%). Furthermore, poorly differentiated type tumors were observed in the grafts obtained from the rectum. This finding was contrary to that for intrinsic rectal tumors, all of which were well differentiated. The histochemical staining of mucin in the tissues from different sites of the large intestine revealed that sulfomucin, which normally exists essentially only in the intrinsic descending colon or rectum, was present in the grafts from the proximal ascending or ascending colon. No gastric tumors were observed in the control rats, which received either DMH or sham operations alone. Tumors in the intrinsic large intestine were observed only in rats that received DMH. These results indicate that colorectal mucosa implanted into the glandular stomach, like the intrinsic large intestine, is still sensitive to tumorigenesis caused by DMH.     

The effects of cold preservation and subimmunosuppressive doses of FK506 on axonal regeneration in murine peripheral nerve isografts

BACKGROUND:

FK506 is a frequently used immunosuppressant with neuroregenerative effects. The neuroregenerative and immunosuppressive mechanisms of FK506, however, are distinct, suggesting that FK506 may stimulate nerve regeneration at lower doses than are needed to induce immunosuppression. The effects of cold preservation, a technique known to improve axonal regeneration through nerve allografts, are not well studied in nerve isografts and are also reported here.

OBJECTIVES:

To determine the effects of subimmunosuppressive doses of FK506 and cold preservation on nerve regeneration in isografts.

METHODS:

The neuroregenerative properties of immunosuppressive and subimmunosuppressive doses of FK506 were compared in a murine model receiving either fresh or cold preserved nerve isografts. Sixty female BALB/cJ mice were randomized into six groups. Animals in groups I, III and V received fresh nerve isografts. Animals in groups II, IV and VI received cold-preserved nerve isografts. Mice in groups I and II received no medical therapy, while those in groups III and IV received subimmunosuppressive doses of FK506, and those in groups V and VI received immunosuppressive doses as confirmed by mixed lymphocyte reactivity assays. Nerve regeneration was evaluated with histomorphometry and functional recovery was evaluated with walking track analysis.

RESULTS:

Pretreatment with cold preservation did not significantly affect neural regeneration. The potent neuroregenerative effect of immunosuppressive doses of FK506 was confirmed, and the ability of subimmunosuppressive doses of FK506 to stimulate axonal regeneration in murine nerve isografts is reported.

CONCLUSIONS:

Less toxic subimmunosuppressive doses of FK506 retaining some neuroregenerative properties may have a clinical role in treating extensive nerve injuries.     

大鼠肝移植急性排斥反应的淋巴细胞蛋白质组学研究

目的 利用差异蛋白质学寻找肝移植急性免疫排斥反应相关功能蛋白.方法 选取SD大鼠与Wistar大鼠,建立大鼠同种异体肝移植的动物模型(急性排斥组)和大鼠同基因移植的动物模型(对照组);使用组织化学方法 对移植肝脏进行形态学观察;利用ELISA检测受体血清细胞因子;通过双向凝胶电泳分离急性排斥组和对照组肝移植后受体大鼠脾脏的淋巴细胞蛋白质,通过软件比较两组蛋白质的质纹图谱,进行差异点分析;选取差异点用基质辅助激光解析-飞行时间质谱进行蛋白鉴定;选取部分鉴定蛋白通过Western blot法进行检测,验证蛋白质组学的分析结果 .结果 ELISA检测结果 表明,移植术后3 d同种异体肝移植大鼠血清中IL-2和IFN-γ的表达上调;急性排斥组肝组织HE染色切片证实均有Ⅱ a～Ⅱ b级(Banff标准)排斥反应表现;差异蛋白质组学分析共鉴定出25个淋巴细胞蛋白质在急性排斥反应中的表达量发生了改变,其中13个蛋白点表达上调,12个蛋白点表达下调;Western blot法验证结果 显示,其中的2个相关蛋白(β-actin和碳酸酐酶)在急性排斥反应中的表达量变化与差异蛋白质组学分析结果 一致.结论 本实验筛选出25个大鼠肝移植急性排斥反应的相关功能蛋白,其中的β-actin和碳酸酐酶在排斥反应中有重要功能,为进一步系统研究这一免疫学现象奠定了基础.