Diagnostic Electron Microscopy (EM)

在多种肿瘤和非肿瘤疾病的诊断中，透射式电子显微镜(EM)被用作一种辅助程序，在精心选择的诊断难题中，它是非常有用的。该服务由CAP定期检查和认证，是NIH园区唯一通过CAP认证的诊断EM服务。<br>去年共处理了118起案件，其中一些案件的样本不止一个。此外，对227个研究样本进行了处理和评估，以支持不同NCI/NIH调查人员的实验研究。其中33个样本需要免疫标记以在超微结构水平上进行蛋白质定位。<br>提交给我们进行超微结构评估的诊断标本来自NCI/NIH方案治疗的患者，在诊断和科学方面具有挑战性。由于NCI方案的性质，我们经常第一个描述肿瘤或疾病的不寻常和独特的超微结构表现，或实验性治疗的结果，如以下例子所示：(1)我们首次表明VHL患者的脊髓和神经根组织中出现的无症状间充质肿瘤，不仅由低分化的间质细胞组成，而且由少数间质细胞组成，具有与发育良好的血管母细胞瘤相似的丰富的细胞质空泡化，从而证实了它们之间的组织发生关系。<br>(2)EM检测到细菌在HeLa细胞内聚集，过表达细菌结合受体CLA-1和CLA-2。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，因此可能成为感染性疾病治疗干预的潜在靶点(Vishnyakova TG等人：Proc Natl Acad Sci，in Press)。<br>(3)EM发现有助于表征一种与低促性腺激素减退相关的新型脑白质营养不良。一个特别独特的新特征是我们在一例周围腓肠神经活检的雪旺细胞中发现了髓鞘异常和胆固醇晶体积聚，这导致了对3例相似患者的腓肠神经活检组织中异常脂质成分的研究和随后的鉴定，从而支持了脱髓鞘过程。<br>(4)在与Mattes博士的合作中，我们已经证明了用于治疗淋巴瘤的CD20和HLA-DR抗体在与B淋巴瘤细胞系结合时被结合到一团囊泡中，这些囊泡通过细胞质夹断机制从淋巴瘤细胞表面脱落。这一过程可能会影响这些抗体的治疗效果。<br>(5)EM有助于确定奈非那韦诱导癌细胞死亡的途径，奈非那韦是美国食品和药物管理局批准的HIV蛋白酶抑制剂，可重新定位为癌症治疗药物。<br>

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>