Chaplin M J, Aldrich A D, Stack M J
Veterinary Laboratories Agency, Central Veterinary Laboratory, Addlestone, Surrey.
Res Vet Sci. 1998 Jan-Feb;64(1):41-4. doi: 10.1016/s0034-5288(98)90113-8.
The medulla oblongata of the brains of 71 scrapie-suspect cases were routinely fixed in 10 per cent formal saline and assessed for vacuolation on HE-stained sections. A pool of fresh brain material was also dissected from each animal and extracts prepared for the routine detection of scrapie-associated fibrils by negative stain transmission electron microscopy. The remaining formaldehyde fixed medulla samples, which were not used for the histological examination, were coded and subjected to a pretreatment with sodium borohydride and then processed using the routine fibril detection procedure. Of the 71 samples tested 46 were considered positive by all three test procedures. Sixteen samples were negative for all three tests. Four samples were positive by histopathological examination and positive for fibrils using fresh tissue, but fibrils could not be detected in the fixed tissue preparations. Conversely, there were five fixed samples in which fibrils could be detected which were negative for the other two tests. The fibrils observed in fixed preparations were indistinguishable from those observed in fresh tissue extracts. The sensitivity of the test for fibril detection using fixed tissue was 92 per cent and the specificity 76 per cent. It is concluded that scrapie-associated fibrils can be recovered from formaldehyde fixed tissue, as presented for routine histopathological examination, and therefore the method has potential in the retrospective analysis of archived brain tissue where only fixed material was stored.
对71例疑似羊瘙痒病病例的脑延髓进行常规处理，用10%的甲醛生理盐水固定，然后对苏木精-伊红（HE）染色切片进行空泡化评估。还从每只动物身上切取新鲜脑材料样本，制备提取物，通过负染透射电子显微镜对羊瘙痒病相关纤维进行常规检测。其余未用于组织学检查的甲醛固定延髓样本进行编码，先用硼氢化钠预处理，然后采用常规纤维检测程序处理。在检测的71个样本中，46个样本在所有三种检测程序中均被判定为阳性。16个样本在所有三项检测中均为阴性。4个样本经组织病理学检查呈阳性，新鲜组织中纤维检测呈阳性，但在固定组织制剂中未检测到纤维。相反，有5个固定样本检测到纤维，但其他两项检测为阴性。在固定制剂中观察到的纤维与在新鲜组织提取物中观察到的纤维无法区分。使用固定组织进行纤维检测的试验敏感性为92%，特异性为76%。结论是，对于常规组织病理学检查的甲醛固定组织，可以检测到羊瘙痒病相关纤维，因此该方法在回顾性分析仅保存固定材料的存档脑组织方面具有潜力。
