可诱导性共刺激分子单抗联合细胞毒T淋巴细胞4Ig在大鼠胰腺移植中的作用

目的 探讨可诱导性共刺激分子（ICOS）单抗、细胞毒T淋巴细胞4ig（CTLA41g）阻断共刺激通路对于异基因大鼠胰腺移植的作用及其机制。方法 建立胰腺移植模型，分A组（对照组），B组（CTLA4Ig组），C组（抗ICOS单抗组），D组（联合CTLA4Ig和抗ICOS单抗组）。术后1、4,7d监测血糖，第7天取胰腺做苏木素-伊红染色，脾脏做流式细胞检测CD3^＋CD8^＋T细胞、CD4^＋T细胞、CD4^＋CD25^＋T细胞。结果 与A组比较：B、C、D组排斥反应较A组明显减弱，显著延长了移植物的存活时间。CD3^＋CD8^＋T细胞计数B、C、D与A组比较均有减少，差异有统计学意义（P〈0．01）。CD4^＋T细胞B、D与A组的差异有统计学意义（P〈0．05）。CD4^＋CD25^＋T细胞各组间逐渐升高，差异有统计学意义（P〈0．01）。结论 抗ICOS单抗和CTLA4Ig能有效地抑制大鼠胰腺移植排斥反应，延长移植物存活时间，且联合应用比单一应用更有效。其可能机制为诱导了CD4^＋CD25^＋T细胞的产生。     

大鼠T细胞疫苗的制备及其抗移植皮肤排斥作用的实验研究

目的 探讨T细胞疫苗(TCV)的制备方法及其抗移植皮肤排斥反应的作用.方法 制备针对特定SD大鼠的供体特异性T细胞疫苗,将其免疫受体Wistar大鼠;然后取免疫前和每次免疫后第五天的受体Wistar的淋巴细胞(反应细胞)与供体SD的淋巴细胞(刺激)进行体外单向混合淋巴细胞反应(MLR),以MTT法检测细胞免疫增值反应情况,比较疫苗接种后诱导淋巴细胞反应受抑制的情况:再将SD大鼠皮肤移植到TCV免疫后的Wistar大鼠,观察皮肤移植反应并统计移植物存活的时间.排斥反应的移植物行病理检查.结果 TCV组受体淋巴细胞反应程度比接种前显著减弱(P＜0.05);特异性TCV组皮肤移植物存活时间较非特异性TCV组及对照组延长(P＜0.05).移植皮肤排斥反应病理表现更轻.结论 TCV经腹腔接种可以诱导出针对同种抗原特异性免疫耐受,TCV能够延长同种异体移植皮肤的存活时间,有一定抗移植排斥反应作用.     

靶向CD40的shRNA干扰抗大鼠异体肢体移植急性排斥反应的实验研究

目的 探讨靶向CD40的RNA干扰对大鼠异体肢体移植急性排斥反应的影响. 方法以纯系SD大鼠为供体,纯系Wistar大鼠为受体,行同种异体右后肢移植.27只大鼠肢体移植后随机分为三组,A组:注射入梭华.Sofast.siCD40-2/pSilencer载体复合物600 μL;B组:注射Sofast-pSilencer4.1-CMV neo空载体复合物600 μL;C组:注射生理盐水600μL,以上均通过阴茎背静脉注射.观察移植物排斥反应征象及存活情况,并于第7天对产生免疫耐受大鼠进行混合淋巴细胞反应,同时进行组织学检查. 结果与B、C组相比,A组移植物发生排斥反应的时间及存活时间均显著延长,差异有统计学意义(P＜0.01)(＞13 d),未见排斥反应征象;B、C组均于术后近期发牛排斥反应.A组大鼠对供体的淋巴细胞呈现低反应性,移植的供体同系大鼠的肢体得以存活. 结论术后不应用免疫抑制剂的情况下,靶向CD40的shRNA干扰可以抗大鼠异体肢体移植急性排斥反应.     

大鼠肝肾联合移植供体DC细胞迁移诱导的免疫保护作用

目的探讨供体DC细胞迁移对肝肾联合移植免疫保护的诱导作用及机制。方法60只大鼠肝肾联合移植免疫排斥模型(选择DA大鼠为供体,Lewis大鼠为受体),随机分为3组：A组：白细胞介素(IL)-10处理的DC细胞干预组；B组：未经IL-10处理的DC细胞干预组；C组：空白对照组。利用所建立的大鼠肝肾联合移植模型结合成熟前期DC细胞进行研究,首先进行供体大鼠DC细胞的预先分离、培养和IL-10处理,然后输入肝肾联合移植后的受体大鼠体内,分析其对肝、肾移植物的免疫保护以及其对移植物和受体存活时间的影响。结果A组肝肾移植的急性排斥反应受到明显的抑制,平均存活(20．0±2．6)d；B组和C组均表现为典型的重度急性排斥反应,存活时间分别为(6．7±0．8)和(7．5±0．5)d；A组与B、C两组受体的累积生存率差异有统计学意义(P＜0．05)。结论IL-10预处理的DC细胞可以对大鼠肝肾联合移植中的移植物起到免疫保护作用；供体的成熟前期DC细胞迁移到受体组织内,能够抑制肝肾联合移植急性排斥反应,并延长肝、肾移植物和受体大鼠存活时间。     

供体骨髓细胞输注诱导大鼠肢体移植免疫耐受

目的 探讨环磷酰胺(CP)加供体脾细胞输注联合供体骨髓细胞(DBMC)输注诱导大鼠肢体移植免疫耐受的效果及机制.方法选择25只雄性Wistar大鼠、25只雌性SD大鼠分别作为肢体移植的供体和受体.实验分为五组:A组:无处理对照组,B组:受体在肢体移植前给予供体脾细胞输注预处理;C组:受体在肢体移植前给予CP预处理,D组:受体在肢体移植前给予供体脾细胞输注加CP预处理,E组:受体在肢体移植前给予供体脾细胞输注联合DBMC输注加CP预处理,每组5只.建立肢体移植动物模型,诱导耐受后观察大鼠一般情况,移植肢体排斥反应出现时间及存活时间,通过混合淋巴细胞培养确定耐受状态,采用PCR检测嵌合体的形成.结果 E组肢体移植物的存活时间[(27.6±1.1)d]较A组[(6.8±0.4)d]、B组[(7.2±0.8)d]、C组[(7.8±1.3)d]、D组[(17.8±0.8)d]显著延长,差异均有统计学意义(P＜0.01).混合淋巴细胞反应E组特异性抑制率[(88.00±1.06)%]显著高于B组[(36.90±1.08)%]、C组[(37.90±0.95)%]和D组[(67.20±1.12)%],差异均有统计学意义(P＜0.01).E组嵌合体呈阳性.结论联合CP加供体脾细胞输注及DBMC输注可一定程度诱导大鼠同种异体肢体移植的免疫耐受,延长移植物存活时间.嵌合体的形成可能与免疫耐受的形成及维持有关.     

阻断共刺激通络抑制大鼠肝移植急性排斥反应的研究

目的研究CD40Ig阻断共刺激通路在大鼠肝移植急性排斥反应中的作用.方法用"二袖套法"行Lewis到Brown Norway(BN)大鼠肝移植32例.A组10例为对照组;B组11例,术中肝脏冷保存前门静脉注射Lipofectamine2000-pcDNA3.1空载体复合物,行肝移植;C组11例,肝脏冷保存前门静脉注射Lipofectamine2000-pcDNA3.1 CD40Ig复合物.术后第5天每组杀死BN 3只,取病理并用细胞凋亡的原位检测法检测肝脏凋亡情况,免疫组织化学检测CD40Ig表达,取脾脏分离淋巴细胞,混合淋巴细胞反应观察刺激指数,流式细胞仪检测与CD40Ig结合的T淋巴细胞比例.余大鼠观察生存情况.死亡大鼠观察病理变化.结果 A组平均存活时间(11.00±4.28) d,B组平均存活时间(12.75±5.57) d,C组平均存活时间(41.25±13.70) d(P<0.01).A组、B组病理示中、重度急性排斥反应,凋亡指数分别为33.67±5.69、39.00±5.29,C组免疫组织化学示CD40Ig表达,第5天病理示轻度急性排斥反应,凋亡指数为0.27±0.21(P<0.01),死亡大鼠病理示部分呈中度急性排斥反应,大部分示慢性排斥反应.混合淋巴细胞反应示C组Lewis大鼠对BN大鼠产生特异性耐受.流式细胞仪示与CD40Ig结合的T细胞占总T细胞11.57%.结论供体肝脏转染CD40Ig能有效阻断T细胞共刺激通路,特异性抑制急性排斥反应,延长受体存活时间,但对慢性排斥反应无效.     

CTLA4Ig和西罗莫司短期联合使用延长异种胰岛移植物的存活

目的 观察细胞毒性T淋巴细胞相关抗原4融合蛋白(CTLA4Ig)与西罗莫司(SRL)联用阻断共刺激通路对异种胰岛移植物存活的影响.方法 取C57BL/6小鼠,腹腔注射链佐星,制成糖尿病模型.采用随机单位组设计分组法将糖尿病小鼠分为7组,各组均于小鼠左肾包膜下移植SD大鼠胰岛300胰岛当量.CTLA4Ig组分别于移植当天及移植后第2、4、6天腹腔注射CTLA4Ig 0.5 mg/d;SRL组分别于移植当天及移植后第1、2天给予SRL灌胃,0.2 mg·kg-1·d-1,其后隔天用药1次,共用2周;MRI组分别于移植当天及移植后第2、4天腹腔注射仓鼠抗小鼠CD154单克隆抗体(MR1)0.5 mg/d;CTLA4Ig和SRL联用组(SRL联用组)、CTLA4Ig和MRl联用组(MR1联用组)以及CTLA4Ig、MR1和SRL联用组(三药联用组)各药物的剂量与用法同上述各组;对照组仅行胰岛移植,不予以药物.观察至移植后200 d,通过监测受者血糖水平来判断排斥反应的发生情况.记录各组移植物的存活(即无排斥反应)时间.发生排斥反应者,或未发生排斥反应、移植物存活时间＞200 d者,取移植胰岛,行HE染色及免疫荧光染色,进行组织学观察.结果 对照组移植物存活时间中位数为17 d,该组最终均发生排斥反应.SRL组、MRl组和CTLA4Ig组移植物存活时间中位数分别为34 d、98 d和77 d.均明显长于对照组(P＜0.05),三组中分别有90%(9/10)、62.5%(5/8)和83.3%(5/6)的小鼠发生排斥反应.SRL联用组移植物存活时间中位数为130 d,明显长于上述4组(P＜0.01),有50%(3/6)的小鼠发生排斥反应.MR1联用组以及三药联用组移植物存活时间中位数均＞200 d,分别有42.9%(3/7)和25%(2/8)的小鼠发生排斥反应.组织学检查结果显示,对照组发生排斥反应时,其移植胰岛破坏严重,可见大量CD4+和CD8+淋巴细胞及巨噬细胞浸润,并可见IgG、IgM和补体C3沉积.其它组发生排斥反应者的组织学改变与对照组相似.SRL联用组存活200 d的小鼠,其移植胰岛组织中未见或仅有少量炎症细胞浸润,胰岛素和胰高血糖素染色阳性,未见IgG、IgM和补体C3沉积.结论 短期联合使用CTLA4Ig和SRL能显著延长小鼠体内大鼠来源的胰岛的存活时间.     

抗原特异性CD4+CD25+T细胞对同种异体胰岛移植影响及作用机制研究

目的:探讨抗原特异性CD4+CD25+Treg细胞免疫对同种异体胰岛急性移植排斥反应的影响和机制。方法:用MACS分选供体抗原特异性CD4+CD25+Treg细胞免疫糖尿病BALB/cByJ受体小鼠，以ICR小鼠胰岛为供体行同种异体胰岛移植。观察移植后小鼠的存活时间、移植前后外周血CD4+和CD8+T细胞亚群的变化和移植物中Th1/Th2细胞因子mRNA表达水平的变化。结果:抗原特异性Treg细胞联合胰岛移植组(C组)胰岛移植物平均生存期为(34.57±17.15)d，显著长于单纯胰岛移植组(B组)的(10.6±1.82) d (P<0.01)；移植后第3天，C组外周血CD4+/CD8+的值显著低于B组(P<0.01)；C组移植物中IL-10,TGF-β mRNA表达比B组显著增强。B组移植物中IL-1β，IL-2及IFN-γ mRNA表达明显强于C组。结论:抗原特异性CD4+CD25+ Treg细胞可通过调节Th2/Th1之间的反应平衡而延长同种异体胰岛移植物的存活时间。     

1,25-(OH)2D3对小鼠皮肤移植后脾T细胞亚群、MLR及NK细胞活性的影响

目的探讨1,25-二羟维生素D3[1,25-(OH)2D3]抑制机体免疫功能的机理,为用于临床抗排斥治疗提供实验依据.方法建立不同系小鼠间皮肤移植的动物模型.术日将实验小鼠随机分为四组,均用小鼠灌胃器给药.对照组:每日20ml/kg生理盐水; 维生素D3(VD3)组:单独应用1,25-(OH)2D3 2.5μg*kg-1*d-1; 环孢素A(CsA)组:单独应用CsA 25mg*kg-1*d-1; VD3+CsA组:联合应用VD3+CsA,按VD3组和CsA组用药剂量给药.术后10d,测定小鼠脾的T细胞亚群、单向混合淋巴细胞反应(MLR)、自然杀伤细胞(NK)活性.结果 VD3组的移植皮片存活时间(13.13±1.13)d,明显长于对照组的(9.75±0.89)d;CD3+、CD4+ T细胞百分率40.19%±4.25%、24.65%±3.47%均明显低于对照组48.70%±7.19%、 33.55%±4.34%,P<0.01;对BALB/C鼠的MLR(0.95±0.12)明显低于对照组(1.19±0.22),P<0.05; NK细胞的活性与对照组小鼠比较, 差异无显著性.结论 1,25-(OH)2D3能延长小鼠皮肤移植的存活时间,其抑制机体免疫功能的作用是通过减少CD3+、CD4+ T细胞的数量及抑制T细胞功能而发挥的,对NK细胞活性无明显影响.     

细胞凋亡诱导大鼠肝移植免疫耐受的实验研究

目的:探讨细胞凋亡诱导移植受体存活的影响,并分析骨髓细胞输注诱导移植肝早期存活的机制。方法:Kamada法建立大鼠肝移植模型,随机法分4组(n=8)。A组:同品系移植组;B组:免疫排斥组;C组:B组+免疫抑制剂;D组:C组+骨髓细胞输注。流式细胞和TUNEL法检测外周血和移植物细胞凋亡。结果:术后第6天移植肝和外周血中凋亡细胞存在,D组中细胞凋亡发生率明显高于B组和C组,凋亡细胞为浸润细胞和肝实质性细胞;D组浸润淋巴细胞为主。细胞凋亡和移植肝组织中TGF-β1mRNA表达相关。结论:移植物中早期的细胞凋亡可能和移植免疫耐受诱导有关,供体骨髓细胞输注在一定程度上是通过细胞凋亡的发生来诱导移植物的早期存活。     

大块异体骨和混合颗粒骨移植在严重骨缺损股骨柄翻修术中的应用

目的探讨采用大块异体骨和混合颗粒骨移植对人工全髋关节置换术后股骨严重骨缺损翻修重建的疗效。方法 1999年7月至2006年6月,采用大块异体骨和混合颗粒骨移植翻修股骨严重骨缺损为主的重建人工全髋关节稳定11例11髋。男7例,女4例,翻修时平均年龄58岁（48～81岁）。11例中10例为骨水泥固定型全髋关节假体,1例为非骨水泥固定假体。累及股骨严重骨吸收MalloryⅢC型11例,臼骨吸收5例中PaproskyⅠ或ⅡC型。辐照冻存的大块异体骨覆盖严重股骨缺损节段和混合颗粒骨填充股骨腔内缺损11例。混合颗粒异体骨打压植骨翻修骨水泥杯2例,非骨水泥杯3例。11例患者进行有规则的临床和影像学随访,行Harris评价,对假体和异体骨的移位、松动和并发症进行观察。结果 平均随访8年11个月（6～11年）。术后Harris评价：其中有9例患者由术前41～49分提高到81～89分,有2例提高到90～95分。术后疼痛（VAS）评分：平均提高至13.1分（11～20分）,比翻修前41.7分（39～44分）明显改善。并发症：术后3个月发现股骨柄旋转移位,有1例出现前倾角缩小3°,到最后随访时再无移位;1例出现术后切口溢液,21d后自愈。所有11例患者的大块异体骨和混合颗粒骨在X线中均显示整合血管化良好,骨小梁通过宿主骨。结论 大块异体骨和混合颗粒骨移植是翻修严重股骨缺损的有效方法,并能充分整合成周围的宿主骨。     

Renal allograft immunosuppression

We have investigated the impact of triple drug immunosuppression on the occurrence of early inflammatory episodes, as detected by fine needle aspiration biopsy, and of episodes of clinical rejection during the immediate postoperative period. The prospective component of this study includes 128 consecutive first cadaveric renal transplant recipients receiving triple drug treatment consisting of azathioprine (Aza), cyclosporin (CyA) and methylprednisolone (MP). For controls we have used three historical groups: one immunosuppressed with Aza and MP (group A), another with CyA monotherapy (group B), and the third with CyA together with MP (group C) in equivalent drug dosages. On the average, 0.8 episodes of inflammation per patient were recorded during the immediate postoperative period of 30 days with triple drug treatment. This was significantly less than the 1.3 episodes in patients receiving Aza and MP (P<0.01), the 1.7 episodes in patients on CyA monotherapy (P<0.001), or the 1.6 episodes in patients receiving CyA together with MP (P<0.001). Although the first episode of inflammation commenced concurrently in each group and the peak intensity of inflammation was the same, the mean duration of inflammation was significantly shorter-2.7 days-under triple drug treatment than the 7.8–11.7 days for controls (P<0.001). The frequency of rejection episodes under triple treatment was also significantly lower-0.2 per patient-than the 0.8 per patient in controls (P<0.001). The first rejection episode occurred later in the triple drug treatment group-on the average, on day 15.2-than in the historical controls (on days 7.7–11.7). There was, however, no difference in the duration of rejection. There were no differences in patient survival between the four groups. Graft survival was 97% at 10 weeks for triple drug-treated recipients and 79%, 68%, and 87% for first grafts in groups A, B, and C, respectively. Disregarding a minor demographic bias for the triple drugtreated group with respect to preformed antibodies and preoperative dialysis treatment, the study suggests that the triple drug protocol, in the short run, is superior to any conceivable double drug combination or CyA monotherapy.     

Chronic allograft nephropathy

Chronic allograft nephropathy (CAN) is the leading cause of renal allograft loss in paediatric renal transplant recipients. CAN is the result of immunological and nonimmunological injury, including acute rejection episodes, hypoperfusion, ischaemia reperfusion, calcineurin toxicity, infection and recurrent disease. The development of CAN is often insidious and may be preceded by subclinical rejection in a well-functioning allograft. Classification of CAN is histological using the Banff classification of renal allograft pathology with classic findings of interstitial fibrosis, tubular atrophy, glomerulosclerosis, fibrointimal hyperplasia and arteriolar hyalinosis. Although improvement in immunosuppression has led to greater 1-year graft survival rates, chronic graft loss remains relatively unchanged and opportunistic infectious complications remain a problem. Protocol biopsy monitoring is not current practice in paediatric transplantation for CAN monitoring but may have a place if new treatment options become available. Newer immunosuppression regimens, closer monitoring of the renal allograft and management of subclinical rejection may lead to reduced immune injury leading to CAN in the paediatric population but must be weighed against the risk of increased immunosuppression and calcineurin inhibitor nephrotoxicity.     

Renal allograft immunosuppression

Serum lipid and lipoprotein profiles were performed in order to investigate lipid abnormalities 2 years post-transplantation in first cadaveric renal allograft recipients immunosuppressed with cyclosporin (CyA), azathioprine (Aza), and methylprednisolone (MP), or with any combination of two drugs. CyA was used in low doses. Total serum cholesterol, triglyceride, LDL cholesterol, HDL cholesterol, HDL2 cholesterol, HDL3 cholesterol, apolipoprotein A1, and apolipoprotein B were determined in 88 prospectively randomized patients with functioning grafts. When considering only the patients who remained on the original randomized treatment, there were no significant differences between the four groups in any of the measured variables. Mean total cholesterol was highest in the group receiving Aza and MP (6.8 mmol/l) and lowest in the group receiving triple therapy (5.8 mmol/l; NS). Mean triglyceride level was highest in the group receiving Aza and MP (2.3 mmol/l) versus 1.8–2.2 mmol/l in the groups receiving triple therapy, Aza+CyA, and CyA+MP. For all patients mean triglyceride level was highest in the group receiving Aza and MP (2.7 mmol/l) and lowest in the group receiving triple therapy (1.7 mmol/l; P<0.05). Mean HDL cholesterol ranged from 1.5 to 1.6 mmol/l in all groups. Neither CyA concentration nor CyA or MP dose correlated with cholesterol or triglyceride concentration. However, the average MP dose was twice as high in the group receiving Aza and MP as in the other two groups employing steroids. Serum cholesterol and triglyceride concentrations were related to body mass index (r=0.28, P=0.045 and r=0.30, P=0.029, respectively). Hyperlipidemia was most common in the group receiving Aza and MP. The frequency of hypercholesterolemia (serum cholesterol level >6.5 mmol/l) was 18%, 45%, 60%, and 35% for the patients continuing with the originally randomized treatment in the groups receiving triple therapy, Aza+CyA, Aza+MP, and CyA+MP, respectively. In a normal Finnish reference population, 35% of all males and 31% of all females have a serum cholesterollevel above 6.5 mmol/l. Thus, only patients receiving Aza and MP had a clearly higher frequency of hypercholesterolemia than that found in a normal population. Taken together, this study shows no lipid abnormalities associated with the use of low-dose CyA for 2 years after transplantation. Hyperlipidemia occurring after transplantation is probably multifactorial and more associated with other risk factors than with the immunosuppressive therapy.     

Renal allograft immunosuppression

The long-term effects of different immunosuppressive drugs and regimens on renal allograft histology are virtually unknown. Therefore, in order to investigate the long-term effects of triple drug treatment versus different combinations of two immunosuppressive drugs on allograft histology, a prospective, randomized trial was performed. One group received triple therapy consisting of low-dose cyclosporin (CyA), azathioprine (Aza), and methylprednisolone (MP), and three groups received combinations of two drugs, i.e., Aza plus CyA, Aza plus MP, and CyA plus MP. At 2 years, there were no significant differences with regard to graft (80%) or patient (87%) survival, or to graft function between the four groups. After 2 years, a protocol core biopsy was taken of all 102 patients having a functioning graft. Of these patients, 61 (60%) were still following the original, randomized treatment protocol; in the remaining cases, changes had occurred in the original protocol and so these cases were considered drop-outs in this study. Histological specimens were examined blindly by two independent observers. Most of the 34 histological variables examined showed no changes. Diffuse fibrosis was most frequent in the CyA plus MP group (70%) and significantly more severe than in the triple therapy group. Mesangial matrix increase in glomeruli was significantly less common in the triple therapy group (8%) than in any one of the double drug combination groups (47%). Two other changes in glomeruli--Bowman capsular thickening and global glomerular sclerosis--were also less frequent in the triple therapy group.(ABSTRACT TRUNCATED AT 250 WORDS)     

Renal allograft immunosuppression

A prospective randomized study was conducted to evaluate the impact of four different conversion protocols on graft outcome in long-term follow-up. Between January 1986 and May 1987, 128 patients with first cadaveric kidnery allografts were randomized at the time of transplantation to four treatment groups of 32 patients each, to be assigned 10 weeks post-transplantation. During the first 10 weeks, all patients received triple therapy with low-dose azathioprine (Aza), cyclosporin (CyA), and methylprednisolone (MP). After 10 weeks, one group continued with triple therapy (group A) while the three other groups received different combinations of two drugs, namely, Aza and CyA (group B), Aza and MP (group C), or CyA and MP (group D). Withdrawal of MP (group B) or especially of CyA (group C) was associated with 4/29 (14%) and 10/28 (36%) acute rejection episodes, respectively, for 60 days after conversion. All rejections were mild and reversible. There were no rejections after Aza withdrawal or in the group that continued on triple therapy during the corresponding time period. The most common reason for dropping out after withdrawal, for those patients who could not continue on the originally randomized medication, was azathioprine intolerance (n=12). Five patients were switched back to triple therapy after CyA withdrawal due to rejection. Steroid intolerance was rare and CyA in low doses was very well tolerated. At 1 year there were no statistically significant differences in graft survival between groups A, B, C, and D-81%, 88%, 88%, and 88%, respecively-or in patient survival-88%, 88%, 88%, and 97%, respectively. For those patients continuing with the originally randomized treatment protocol, there were no differences in patient or graft survival either, the means being 91% and 89%, respectively. The most common cause of death after withdrawal was cardiovascular in nature, and there were no more fatal infections under triple drug treatment than with double drug regimens. There were no statistically significant differences in mean serum creatinine values at 1 year. The median serum creatinine values for groups A, B, C, and D were 112, 132, 133, and 133 mol/l, respectively. At 1 year the mean CyA dose in the groups that continued with CyA was 3.5–4.2 mg/kg per day and CyA concentrations were equal.     

Experimental model for allograft incorporation and allograft fracture repair.

This study describes a rat model of allograft osteotomy healing. An intercalary skeletal defect was created in adult Lewis rats by resecting a 2-cm segment of the femur in the diaphysis, including the periosteum and the cuff of muscle layers. The skeletal defects were replaced with fresh-frozen devascularized intercalary allografts from Sprague-Dawley rats. A transverse osteotomy was made in the middle of the allograft. The osteotomized segments were stabilized with an intramedullary threaded Kirschner wire, which allowed immediate ambulation. Radiographic and histological examination at 4 and 8 weeks revealed a characteristic healing process at three different interfaces. Radiographically, the distal metaphyseal host-donor junction healed faster than the proximal diaphyseal host-donor interface. The osteotomy site did not have evidence of an intramembranous or endochondral repair process. This model can serve as a baseline for assessing allograft incorporation and fracture repair.     

Cadaveric allograft microbiology

This study aims to determine the contamination rate of cadaveric bone allograft and blood cultures retrieved from 119 donors within Leicester between 1990 and 2003. A contamination rate of 27% was present, with 120 of 437 bone allografts culturing positive at the time of retrieval. Similarly, a contamination rate of 37% was present, with 40 of 107 blood samples culturing positive. The time interval between death and procurement did not influence blood contamination. Coagulase-negative Staphylococcus was the commonest organism isolated in both blood and bone cultures. One donor had Clostridium grown in their blood culture. The available evidence confirms similar contamination rates with other studies. The majority of organisms isolated were skin commensals with a low rate of contamination of highly pathogenic organisms such as Clostridium.

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Résumé Cette étude a pour but de déterminer le taux de contamination des allogreffes osseuses cadavériques et des hémocultures chez 119 donneurs, entre 1990 et 2003, à Leicester. Un taux de contamination de 27% était présent avec 120 des 437 allogreffes avec une culture positive au moment du prélèvement. De la même façon, un taux de contamination de 37% était présent avec 40 des 107 prélèvements de sang avec une culture le positive. Lintervalle de temps entre la mort et lacquisition du prélèvement na pas influencé la contamination du sang. Le staphylocoque coagulase négative était lorganisme plus fréquent isolé dans le sang et dans los. Un donneur avait un Clostridium dans lhémoculture. Les résultats confirment des taux de contamination voisins de ceux des autres études. La majorité des organismes isolés sont des commensaux de la peau avec un bas taux de contamination dorganismes hautement pathogènes tels que Clostridium.