Diagnostic Electron Microscopy (EM)

透射电子显微镜（EM）被用作一种辅助程序，在广泛的肿瘤性和非肿瘤性疾病的诊断，可以是非常有用的选择诊断困境。该服务由CAP定期检查和认证，是NIH校园内唯一获得CAP认证的诊断EM服务。去年共处理了118个案件，其中一些案件包括多个标本。此外，还对227个研究样本进行了处理和评估，以支持NCI/NIH各调查人员的实验研究。其中33个标本需要在超微结构水平上进行蛋白质定位的免疫标记。提交给我们进行超微结构评估的诊断标本来自NCI/NIH协议治疗的患者，在诊断和科学上具有挑战性。由于NCI协议的性质，我们通常是第一个描述肿瘤或疾病的不寻常和独特的超微结构发现，或实验治疗的结果，如以下例子所示：(1)我们首次发现，在VHL患者的脊髓和神经根组织中出现的无症状间充质肿瘤，不仅包括分化差的间充质细胞，还包括与发育良好的血管母细胞瘤相似的具有丰富细胞质空泡化的少数基质细胞，从而证实了它们之间的组织发生关系。<BR b> (2) EM显示，在过表达细菌结合受体CLA-1和CLA-2的HeLa细胞中，细菌在细胞内积聚。这一新发现具有重要的临床意义，因为它表明这些受体可能促进感染或代表细菌内化和降解的机制，因此可能是感染性疾病治疗干预的潜在靶点（Vishnyakova TG等人：Proc Natl Acad Sci，出版中）。EM结果有助于表征与促性腺功能低下相关的一种新型脑白质营养不良。一个特别显著的新特征是我们在周围腓肠神经活检中发现髓鞘异常和雪旺细胞中胆固醇结晶积聚，这导致了对3名类似患者腓肠神经活检中异常脂质组成的研究和随后的鉴定，从而支持脱髓鞘过程。在与Mattes博士的合作中，我们证明了用于淋巴瘤治疗的CD20和HLA-DR抗体，当与b淋巴瘤细胞系结合时，会合并成一团囊泡，这些囊泡通过细胞质挤压机制从淋巴瘤细胞表面脱落。这个过程可能会影响这些抗体的治疗效果。(5) EM有助于表征奈非那韦诱导的癌细胞死亡途径，奈非那韦是一种食品和药物管理局批准的HIV蛋白酶抑制剂，可以重新定位为癌症治疗药物

Transmission electron microscopy (EM) is used as an adjunct procedure in the diagnosis of a wide range of neoplastic and non neoplastic diseases and can be extremely useful in well chosen diagnostic dilemmas. The service is regularly inspected and certified by CAP, and is the only diagnostic CAP-certified EM service on NIH campus. <BR> A total of 118 cases were processed last year, some consisting of more than one specimen. In addition, 227 research specimens were processed and evaluated to support experimental studies of various NCI/NIH investigators. Thirty three of these specimens required immunolabeling for protein localization at the ultrastructural level. <BR> The diagnostic specimens that are submitted to our service for ultrastructural evaluation come from patients treated in NCI/NIH protocols and are diagnostically and scientifically challenging. Due to the nature of the NCI protocols, we are often the first to describe the unusual and unique ultrastructural findings of a tumor or disease, or the outcome of experimental treatments, as demonstrated in the following examples: <BR) (1) We showed for the first time that asymptomatic mesenchymal tumorlets arising in the spinal cord and nerve root tissue of VHL patients, consist not only of poorly differentiated mesenchymal cells, but also of a few stromal cells with abundant cytoplasmic vacuolization similar to those seen in well developed hemangioblastomas, thus confirming their histogenetic relationship. <BR> (2) EM demonstrated intracellular accumulation of bacteria in HeLa cells overexpressing bacteria-binding receptors CLA-1 and CLA-2. This novel finding has important clinical implications, because it shows that these receptors may either facilitate infection or represent a mechanism of bacterial internalization and degradation and therefore, may be potential targets for therapeutic intervention in infectious diseases (Vishnyakova TG, et al: Proc Natl Acad Sci, in press).<BR> (3) EM findings were instrumental in the characterization of a novel form of leukodystrophy associated with hypogonadotropic hypogonadism. A particularly distinguishing novel feature was our finding of myelin sheath abnormalities and cholesterol crystal accumulation in Schwann cells of a peripheral sural nerve biopsy, which led to the study and subsequent identification of abnormal lipid composition in sural nerve biopsies from 3 similar patients, thus supporting a demyelinating process. <BR> (4) In collaboration with Dr. Mattes, we have shown that the CD20 and HLA-DR antibodies, which are used in the treatment of lymphomas, when bound to a B-lymphoma cell line are incorporated into a conglomerate of vesicles, which are shed from the surface of the lymphoma cells by a cytoplasmic pinched-off mechanism. This process may affect the therapeutic efficacy of these antibodies. <BR> (5) EM was instrumental in characterizing pathways of cancer cell death induced by nelfinavir, a Food and Drug Administration-approved HIV protease inhibitor, which could be repositioned as a cancer therapeutic.<BR>