Comparative dose-dependence study of FK506 on transected mouse sciatic nerve repaired by allograft or xenograft

We evaluated the effects of FK506, at doses of 0.2, 2, and 5 mg/kg/day, on the response to nerve grafts implanted in outbred mice. A 6 mm long segment of the sciatic nerve was transected and repaired by autograft (the same segment resected), allograft (from another mouse), or xenograft (from a rat nerve). The regenerating nerves were harvested after 3 weeks and studied under light and electron microscope. Allografts of animals treated with the 5 mg/kg/day dose of FK506 appeared similar to those from autografts, demonstrating an equivalent number of myelinated fibers. In mice treated with the 2 mg/kg/day dose, regeneration was slightly hindered, as indicated by the reduced number of myelinated fibers. In contrast, in mice given a 0.2 mg/kg/day dose of FK506, allografts were not different from untreated allografts; both groups showed a marked rejection response with only few unmyelinated axons and no myelinated fibers. Xenografts showed a more severe rejection than allografts, with a marked inflammatory cell reaction throughout the graft. In contrast, in mice treated with the 5 mg/kg/day dose, xenografts exhibited a mild cell reaction and a greater number of regenerated myelinated fibers. In conclusion, effective axonal regeneration is achieved with FK506 administration at doses of 5 mg/kg/day through allografts and, partially, through xenografts.     

解剖型同种异体皮质骨环在颈椎前路椎间融合中的应用

目的 探讨解剖型同种异体皮质骨环(AACR)在颈椎前路椎间融合中的应用.方法 对9例颈椎间盘突出患者,用AACR及颈椎前路钢板进行颈椎前路椎间融合手术,植入10个椎间隙.术后观察临床效果及手术并发症,并行X线评估.结果 9例患者随访13～18个月,平均16.2个月.术后及随访时的Cobb角度及椎间隙高度均较术前明显恢复,术后疗效评分平均改善率为84.5%.结论 AACR上下面的倒锯齿状设计使得AACR植入牢固,两侧的微孔设计利于植骨的爬行替代;由于保留了皮质骨,具有类似金属支架的支撑作用.     

Tracheal Transplantation: Superior and Inferior Thyroid Artery Perfusion Territory

Objective: To determine the perfusion territories of the superior and inferior thyroid arteries in humans. Tracheal transplantation is a potential option for management of long-segment tracheal stenosis. However, the maximum length of vascularized trachea that can be reliably transplanted has not been established. Study Design: The tracheal vascular territory of individual superior and inferior thyroid arteries was determined separately in 10 humans postmortem. Methods: India ink was infused unilaterally under controlled pressure into the superior (n = 5) and inferior (n = 5) thyroid arteries of cadaveric tracheas. Tracheas were sectioned longitudinally and the caudalmost extent of mucosal dye staining was determined via microscopic assessment. Results: The tracheal perfusion territory of the superior thyroid artery was two to five rings (1.7 ± 0.5 cm) and the inferior thyroid artery, nine to 13 rings (6.5 ± 1.1 cm). In both cases, the tracheal mucosa on the contralateral side was stained to the same caudal level. Conclusions: The inferior thyroid artery was shown to perfuse the trachea maximally to the 13th ring (8.1 cm). As such, the unilateral inferior thyroid artery would serve as a suitable vascular component for long-segment tracheal transplantation in humans.     

Novel phenotype associated with in vivo activated CTL precursors

A previously undefined phenotype of CD8(+) cells that appears to represent in vivo activated CTL precursors (CTLP*) has been identified in the spleens of C57Bl/6 mice responding to a P815 tumor allograft. This population was first evident by the transient expression of very high levels of CD28 and CD44 on day 5 of the allograft response and reached maximal levels on days 7 and 8 before declining on day 9. A transient increase in CD69 expression was also observed on these cells on day 5. In contrast, CTL effectors (CTLE), identified by their CD8(+)CD44(hi)CD62LloCD45RBlo phenotype, were not appreciably detected in the spleen until day 8 and reached maximal levels on day 10. Further characterization of CTLP* on day 7 revealed that they represented blasting cells by increased light scatter and also expressed very high levels of CD54 but not CD122, CD152, or CD154. In addition, the cells had already up-regulated CD49d, asialo GM1, CD11a, and CD95L, and down-regulated their expression of CD62L. A small percentage of these cells also expressed CD25. Day 7 CTLP* sorted on the basis of their CD44(xhi) and CD54(xhi) phenotype did not exhibit cytolytic activity in a standard chromium release assay but became cytotoxic when they were cultured in the presence of exogenous murine IL-2 for 5 days. Granzyme B activity, however, was detected in CTLP* on day 7 at levels equivalent to CTLE on day 10. In order to establish a potential precursor relationship between CTLP* and CTLE, mice were treated with various doses of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a chemical that has been shown to dose-dependently suppress the in vivo generation of CTLE to P815 tumor cells by altering an early stage of CTLP activation. Results indicated that CTLP* were suppressed by TCDD on day 7 to the same degree that CTLE were suppressed on day 10. Importantly, for controls and for all doses of TCDD, there were approximately 12.5 CTLE on day 10 for every CTLP* detected on day 7. These results suggested that TCDD acted identically across all doses to inhibit the early stages of activation of CTLP but did not affect the final stages of differentiation and expansion to CTLE. This interpretation supports the previous observation that TCDD exposure had to occur within the first 3 days of the allograft response in order to induce suppression of CTLE activity. Taken together, these results support the conclusion that in vivo activated CTLP can be identified by their unique expression of very high levels of CD44, CD28, and/or CD54 prior to their full maturation and clonal expansion to functional CTLE.     

Immunomodulatory effect of extracorporeal photopheresis after successful treatment of resistant renal allograft rejection

BACKGROUND: Acute renal allograft rejection contributes to patient morbidity. Standard immunosuppressives are only partially effective and have significant side effects. Extracorporeal photopheresis (ECP) has been effective in reversing the acute rejection process. T cell cytokine expression is implicated in rejection and tolerance but actual changes in the cytokine profile of ECP-treated individuals have not been documented. METHODS: ECP was administered to a patient with acute renal allograft rejection resistant to other immunosuppressives. Enzyme-linked immunosorbent spot (ELISPOT) assay was performed to determine the frequency of mitogen-induced cytokine-producing cells before and after ECP. RESULTS: ECP resulted in resolution of rejection; serum creatinine concentration fell from 7.1 to 2.2 mg/dl; ELISPOT revealed a three-fold increase in the frequency of IL-5 producing cells; IFN-gamma:IL-5 ratio shifted from 2.73 pre-treatment to 1.01 post-treatment. CONCLUSION: Effective therapy of acute allograft rejection with ECP alters the peripheral blood cytokine profile towards "type 2" cytokines, suggesting that alteration of T cell cytokine profiles may contribute to the resolution of the process.     

同种异体新鲜半月板移植的实验研究

目的探讨治疗半月板损伤的新途径.方法34只健康家犬随机分成3组26只动物的左膝为A组,右膝为B组,另8只动物的双膝为C组.A组单纯切除内侧半月板;B组切除内侧半月板后,将从另一动物右膝关节取下的内侧半月板植入原位;C组作为正常对照.分别于术后4、8、12周各处死2只动物,移植物进行大体观察,组织学、组织化学及电镜观察.16周时,2只动物行动脉灌注,23只动物标本行生物力学试验.留3只动物以作远期观察.结果移植半月板组织能存活.生物力学试验结果显示植入半月板明显提高了膝关节的力学性能,特别是在负重时.结论初步认定同种异体新鲜半月板能够同宿主良好愈合,并能在移植后短期随访过程中保持正常的结构和功能,从而防止或延缓了膝关节的退变.     

Partial Artificial Heart (ALVAD) Use with Subsequent Cardiac and Renal Allografting in a Patient with Stone Heart Syndrome

The abdominal left ventricular assist device (ALVAD) is an order of magnitude more effective than conventional intra-aortic balloon pumping (IABP) in unloading and providing circulatory support to the failing left ventricle. This is a report of a unique case which demonstrates that in the absence of pulmonary vascular obstruction or constriction, the ALVAD can substitute for both left and right heart function. A 21-year-old patient with a congenital bicuspid aortic valve developed acute valvular endocarditis which rapidly progressed to congestive heart failure. An operation was undertaken, the mitral and aortic valves were excised and replaced by porcine heterografts, and a fistula from the right sinus of Valsalva to the right ventricle was closed. When coronary circulation was restored, irreversible ischemic contracture of the left ventricle, or "stone heart" syndrome, developed and emergency ALVAD or partial artificial heart implantation was effected. This device functioned as a total artificial heart for nearly six days, while a donor heart was sought. The patient then underwent removal of the ALVAD and cardiac and renal allografting. The transplanted heart functioned well, but the patient expired fifteen days later from gram-negative sepsis.     

Improved long-term allograft function in pediatric renal transplantation with mycophenolate mofetil

MMF has been shown to decrease the incidence of acute rejection in children and adults at 1 and 3 yr. Other beneficial effects of MMF have been more difficult to demonstrate. Our open-labeled study presents a 5-yr data for patients and graft survival, allograft function, and growth in MMF-treated patients. The trial included 29 patients who were treated with MMF in combination with cyclosporine and methylprednisone. Patients were compared with a preceding group of 29 patients treated with AZA instead of MMF. Patient and graft survival rate 5 yr after transplantation were 97 and 90% in the MMF group vs. 93 and 83% in the AZA group (p: NS). Acute rejection was 20.6% in the MMF group vs. 58.6% in the AZA group (p < 0.01). Chronic rejection was 10.3% in the MMF group and 25% in the AZA group (p: NS). The changes in the creatinine clearance from baseline to 5 yr (Delta) were different between groups (-6.0 +/- 5.1 mL/min/1.73 m(2) in the MMF group vs. -22.2 +/- 7.6 mL/min/1.73 m(2) in the AZA group, p < 0.05). Also, the slope of 1/Scr showed a significant lower incidence of worsening renal function after the second year of renal transplantation (p < 0.0001) in the MMF group compared with the AZA group. Delta Height SDS in prepubertal patients was 0.3 +/- 0.4 SDS in the MMF group vs. -0.8 +/- 0.2 SDS in the AZA group (p < 0.05). This study shows that long-term MMF therapy has resulted in a decrease in acute rejection and was associated with a protection against renal function deterioration. The use of MMF enables a reduction in the dose of steroids and leads to a linear growth improvement of children after renal transplantation.     

Positive culture in allograft ACL-reconstruction: what to do?

The transmission of disease or infection from the donor to the recipient is always a risk with the use of allografts. We carried out a research study on the behavioural pattern of implanted allografts, which were initially stored in perfect conditions (all cultures being negative) but later presented positive cultures at the implantation stage. Because there is no information available on how to deal with this type of situation, our aim was to set guidelines on the course of action which would be required in such a case. We conducted a retrospective study of 181 patients who underwent an ACL reconstruction using BPTB allografts. All previous bone and blood cultures and tests for hepatitis B and C, syphilis and HIV were negative. An allograft sample was taken for culture in the operating theatre just before its implantation. The results of the cultures were obtained 3–5 days after the operation. We had 24 allografts with positive culture (13.25%) after the implantation with no clinical infection in any of these patients. Positive cultures could be caused by undetected contamination while harvesting, storing or during manipulation before implantation. The lack of clinical signs of infection during the follow-up of our patients may indicate that no specific treatment—other than an antibiotic protocol—would be required when facing a case of positive culture of a graft piece after its implantation.