Allograft bone matrix versus synthetic bone graft substitutes

Autologous bone is used very often in the treatment of fresh fractures, delayed unions and non-unions. Alternatives have included allografts and in recent years also demineralized bone matrix. The growing availability of good synthetic bone grafts and their advantages in safety and avoiding donor-site morbidity are the reasons that these products are being used more and more. There are on the market a wide variety of substitutes with different capabilities. Nevertheless autologous bone graft is still considered as the gold standard and will be discussed here in that context. Osteoconductive, osteogenic and osteoinductive products will also be classified and their advantages and disadvantages described.     

Aortic Valve Replacement with Cryopreserved PuImonary Allograft

Experimental as well as clinical data support the finding of using the pulmonary valve as a systemic semilunar valve. From January 1990 to December 1992, 89 patients received pulmonary cryopreserved allografts as aortic valve replacement. Sixteen subjects suffering from native or prosthetic valve endocarditis were included. Age ranged from 10 to 74 years. Sixty-five patients received isolated aortic valve replacement and 24 patients required additional surgical measures, such as coronary artery bypass graft, mitral valve reconstruction, replacement of the ascending aorta, supravalvular patch aortoplasty, ventricular septal defect closure, or myectomy. All operations were performed with normothermic bypass and cold cardioplegic arrest. Follow-up is maintained by visits to the outpatient clinic and echocardiographic assessment of the valve status every 3 months during the first year and every 6 months thereafter. There were four early and three late deaths. Four valves had to be removed: one intraoperatively and three 2, 4, and 24 months postoperatively. Echocardiographic assessment proved that gradients across the valve were low or absent. The majority of patients showed trivial or no aortic regurgitation during follow-up. No thromboem-bolic events have been observed and no new endocarditis occurred. Thus, event-free survival at 3 years is 87%. The results with pulmonary allografts have shown to be comparable to aortic allografts. Even in patients with acute native or prosthetic valve endocarditis, the use of cryopreserved pulmonary allografts has shown no adverse effects. We continue to implant cryopreserved pulmonary allografts In the aortic position. The long-term function of the valve, however, must be established, making continued evaluation of postoperative patients mandatory. (J Card Surg 1994;9:43–49)     

The prolongation of local anaesthetic action with dextran

Field blocks of the inguinal region were performed in two groups of patients, in one group using a mixture of 0.5% bupivacaine, 1:200 000 adrenaline and dextran 110 and in the second group using a mixture of 0.5% bupivacaine, 1:200 000 adrenaline and dextran 150; the study being performed in a double-blind fashion. The dextran 150 mixture produced a highly significant increase (p less than 0.01) in the duration of the block when compared with the dextran 110 mixture. The authors conclude that the use of dextran of increasing molecular weight increases the duration of action of local anaesthetics correspondingly.     

Histologic alterations in endometrial hyperplasia and well-differentiated carcinoma treated with progestins

The treatment of complex atypical hyperplasia (CAH) and well-differentiated endometrioid carcinoma (WDC) by progestin therapy has been shown to be a safe alternative to hysterectomy. Accurate assessment for regressive changes induced by the progestins is critical to successful treatment. However, there are few studies detailing the histopathologic changes associated with progestin therapy. A total of 44 patients with CAH or WDC, treated with oral progestins or a progesterone or levonorgestrel-releasing intrauterine device, were followed by endometrial biopsy and/or curettage at 3 to 6 month intervals for a maximum of 25 months. The pretreatment and posttreatment endometrial samples were evaluated for response to treatment and for the histologic features of gland-to-stroma ratio, architectural abnormalities [back-to-back glands and confluency (cribriform and/or papillary patterns)], glandular cellularity, mitotic activity, cytologic atypia, and cytoplasmic changes. Histologic changes seen in progestin-treated endometria included a decreased gland-to-stroma ratio, decreased glandular cellularity, decreased to absent mitotic activity, loss of cytologic atypia, and a variety of cytoplasmic changes including mucinous, secretory, squamous, and eosinophilic metaplasia. Architectural changes tended to resolve later in the course of treatment. Some architectural abnormalities, specifically cribriform and papillary patterns, were induced by progestins mimicking progression. Twelve (67%) of 18 women with CAH had complete resolution, 2 (11%) regressed to complex hyperplasia without atypia, and 4 (22%) demonstrated persistent disease over a median follow-up period of 11 months. Eleven (42%) of 26 women with WDC had complete resolution and 15 (58%) had persistent disease over a median follow-up period of 12 months. Three instances of disease progression occurred, presumably only after discontinuing progestin treatment. Only persistent architectural abnormalities and/or cytologic atypia in the 7 to 9-month biopsies were predictive of treatment failure, with a trend for cytologic atypia to be the most powerful predictor. These findings indicate that progestin therapy should be continued for no less than 6 months to accurately assess treatment response. A modified classification for progestin-treated lesions of the endometrium is proposed.     

Allograft safety: viral inactivation with bone demineralization

A study was performed to validate the effectiveness of a bone demineralization process with respect to its inactivation of viruses. The viruses selected for study included human immunodeficiency virus (HIV), duck hepatitis B virus (a model for human hepatitis B), bovine viral diarrheal virus (a model for human hepatitis C), human cytomegalovirus, and human poliovirus (a model for small nonenveloped viruses, e.g., hepatitis A). This study was performed in compliance with Good Laboratory Practice regulations using validation methodology similar to that used to ensure the safety of blood derivatives and other products. Use of the bone demineralization process described in this report resulted in a reduction in infectivity of greater than one million (10(6)) for all viruses and as much as one trillion (10(12)) for the poliovirus.     

异体脸移植术

异体脸移植术,俗称"换脸",是目前国际上最具挑战性,也最具争议的手术之一,国外多家医疗机构(如英国伦敦皇家自由医院,美国肯塔基州路易斯维尔大学和法国巴黎的一家医疗机构)正在筹备该手术的前期工作, 事实上,2003年9月16日,我国外科医生已经完成了一例最接近于"换脸"的手术.     

Allograft fractures revisited

A retrospective review of patients with allograft fractures was done at the authors' institution. Between 1974 and 1998, 185 of 1046 (17.7%) structural allografts fractured in 183 patients at a mean of 3.2 years after transplantation. Initial allograft fixation included internal fixation with plates and screws in 181 patients. Patients with grafts that were longer than the average length (15.5 cm) tended to have worse results. Adjuvant therapy had no effect on fracture rate. Seventy-three patients with fractures had other allograft complications. Infection and nonunion with allograft fracture significantly worsened the outcome. The incidence of fracture in the patients with osteoarticular and arthrodesis transplants was significantly higher than those patients who had intercalary and composite reconstructions. Treatment of the allograft fractures included open reduction and internal fixation in 41 patients, reconstruction with a new allograft in 38, allograft-prosthesis composite in five, oncologic prosthesis in 19, amputation in 15, arthroscopic removal of loose bodies in three, resurfacing of fractured osteoarticular allograft surfaces in 39, allograft removal and cement spacer placement in 15. Twenty patients did not receive treatment. Eight of the fractures in patients who were not treated healed spontaneously. Outcomes were judged as excellent in nine patients (4.9%), good in 72 patients (38.9%), fair in 17 patients (9.2%), and in 85 patients (45.9%) the allograft reconstruction failed.     

CD44分子在肾移植患者急性排斥反应肾组织中的表达及意义

目的:探讨CD44分子与肾移植急性排斥反应的关系。方法:回顾分析2005年7月～2009年5月间肾移植术后穿刺病理活检证实为急性排斥反应患者28例的CD44在移植肾组织中的表达。结果:28例急性排斥反应肾组织中有25例CD44呈阳性表达,阳性率为89.29%;10例慢性排斥反应肾组织中有3例阳性表达,阳性率为30%;30例正常肾脏组织中5例CD44分子的阳性表达,阳性率为16.7%;两两比较,结果差异有统计学意义(P0.05)。结论:CD44与其与配体的相互作用在移植肾急性排斥反应中可能起到重要作用,CD44分子有可能成为一个特异性和敏感性都较好的早期诊断急性排斥的预测因子。