活性组织工程神经移植体桥接坐骨神经损伤：存活时间及功能恢复的量化评估

目的:利用组织工程方法制备的神经组织替代物桥接大鼠坐骨神经缺损,观察移植体的存活时间和神经功能指数。方法:实验于2001-04/2003-01在宾夕法尼亚大学神经外科颅脑创伤中心实验室完成。实验方法:利用神经轴索可以体外机械拉长的特性,将背根神经节神经元和拉长的轴索经凝胶处理后,一并卷入可吸收的聚乙醇酸导管内,制备出具有生物学活性的组织工程神经移植体。选用成年雄性SD大鼠40只,按随机数字表法分为4组,每组10只。建立大鼠坐骨神经损伤模型,组织工程替代物移植组将长约12mm的组织工程神经移植体桥接于坐骨神经缺损处;自体神经移植组将切除的坐骨神经近远端调转后重新缝合回缺损处;损伤模型组切除神经后无修复;对照组未造成损伤。实验评估:术后15周,分别对各组大鼠进行行为学评估,比较坐骨神经功能指数,其绝对数值与坐骨神经功能呈负相关。术后16周,处死动物前检测坐骨神经的传导速度,处死动物后行病理学检查,坐骨神经标本切片分别行苏木精-伊红、降钙素基因相关的缩氨酸抗体(背根神经节神经元标记物)、神经丝蛋白和髓鞘染色。结果:40只大鼠全部进入结果分析,无脱失。①术后15周,损伤模型组大鼠的坐骨神经功能指数绝对值高于组织工程替代物移植组和自体神经移植组(-94.3±2.55,-80.0±1.2,-82.7±2.7,P<0.05),两移植组差异无显著性意义(P>0.05)。对照组大鼠的坐骨神经功能指数为(-6.08±1.6),其绝对值显著低于其他3组(P<0.05)。②术后16周,对照组、组织工程替代物移植组、自体神经移植组大鼠的坐骨神经传导速度分别为(51.2±3.1,12.4±2.3,12.0±2.5)m/s,损伤模型组无动作电位引出,对照组大鼠的坐骨神经传导速度高于其他各组(P<0.01),两移植组差异无显著性意义(P>0.05)。③术后16周,自体神经移植组和替代物移植组中,大体检查可见相对正常的神经组织通过缺损区,聚乙醇酸导管基本已完全吸收。苏木精-伊红染色在替代物移植组大鼠的损伤区内发现大量的神经元细胞,降钙素基因相关的缩氨酸抗体和神经丝蛋白双重免疫组织荧光化学检查证实为背根神经节神经元。髓鞘染色可见缺损区内大量髓鞘包裹的轴突。结论:组织工程制备的神经组织替代物能够在移植受体内长期存活,并与受体神经结合促进神经功能恢复,在修复神经缺损、促进功能恢复方面与自体神经具有近似的能力。     

Hemorrhagic intracranial malignant neoplasms: spin-echo MR imaging

Twelve patients with 15 separate, spontaneously hemorrhagic, intracranial malignant lesions (seven primary gliomas, eight metastatic lesions) were examined with spin-echo magnetic resonance imaging at 1.5 T, and with computed tomography. The signal intensity patterns of these lesions, as seen on both short repetition time (TR)/short echo time (TE) and long-TR/long-TE spin-echo pulse sequences, were compared with the previously described appearance at 1.5 T of non-neoplastic intracerebral hematomas. The images of hemorrhagic intracranial malignancies showed notable signal heterogeneity, often with identifiable nonhemorrhagic tissue corresponding to tumor; diminished, irregular, or absent hemosiderin deposition; delayed hematoma evolution; and pronounced or persistent edema, compared with non-neoplastic hematomas. The demonstration of these characteristics in the appropriate clinical setting may suggest malignancy as the cause of an intracranial hematoma.     

Complete and partial ureteral obstruction: evaluation of renal effects with P-31 MR spectroscopy and Tc-DMSA scintigraphy

Phosphorus-31 magnetic resonance (MR) spectroscopy was used to study the effects of partial and complete ureteral obstruction on the porcine kidney; results were compared with renal tubular function as determined with technetium-99m dimercaptosuccinic acid (DMSA) scintigraphy. Twenty-seven pigs were used: nine as sham-operated controls, six with partial ureteral obstruction, and 12 with complete ureteral obstruction. P-31 MR spectra and Tc-DMSA scintiscans were obtained weekly over 3 weeks. Partial obstruction caused no significant change in P-31 MR spectra, whereas Tc-DMSA scintiscans showed a 74% decrease in tubular function by the end of 3 weeks. Complete obstruction caused a 43% reduction in the mean adenosine triphosphate (ATP) to inorganic phosphate (Pi) ratio, which paralleled the 96% decrease in Tc-DMSA uptake over 3 weeks. The difference in ATP/Pi ratios between control and completely obstructed kidneys was significant (P less than .01) at 2 and 3 weeks after ligation. These results indicate that radionuclide Tc-99m DMSA uptake is very sensitive to the pathophysiologic changes in renal tubular function, while the organ average cellular bioenergetic state (ATP/Pi) is not as strongly affected.