Antibody−enzyme complexes (AECs) are ideal sensing elements, especially when oxidoreductases are used as the enzymes in the complex, with the potential to carry out rapid electrochemical measurements. However, conventional methods for the fabrication of AECs, including direct fusion and chemical conjugation, are associated with issues regarding the generation of insoluble aggregates and production of homogeneous AECs. Here, we developed a convenient and universal method for the fabrication of homogeneous AECs using the SpyCatcher/SpyTag system. We used an anti-epidermal growth factor receptor (EGFR) variable domain of a heavy chain antibody (VHH) and a glucose dehydrogenase (GDH) derived from Aspergillus flavus (Af GDH) as the model antibody and enzyme, respectively. Both SpyTag-fused VHH and SpyCatcher-fused Af GDH were successfully prepared using an Escherichia coli expression system, whereas anti-EGFR AECs were produced by simply mixing the two fusion proteins. A bivalent AEC, Af GDH with two VHH at both terminals, was also prepared and exhibited an increased affinity. A soluble EGFR was successfully detected in a dose-dependent manner using immobilized anti-EGFR immunoglobulin G (IgG) and bivalent AEC. We also confirmed the universality of this AEC fabricating method by applying it to another VHH. This method results in the convenient and universal preparation of sensing elements with the potential for electrochemical measurement.
Low-grade cribriform cystadenocarcinoma (LGCCA) is a rare tumor of the salivary gland that exhibits clinically indolent behavior. In this paper, we present a case of invasive adenocarcinoma of the accessory parotid gland in a young male that exhibited histology suggestive of an association of LGCCA. A 27-year-old man presented with a subcutaneous tumor in his left cheek. The tumor was separated from the parotid gland and located on the masseter muscle. The tumor was resected, and the postoperative histological diagnosis was adenocarcinoma, not otherwise specified (ANOS). The tumor exhibited papillary-cystic and cribriform proliferation of the duct epithelium and obvious stromal infiltration. Some tumor nests were rimmed by myoepithelium positive for smooth muscle actin, p63, and cytokeratin 14, indicating the presence of intraductal components of the tumor. Tumor cells exhibited mild nuclear atypia, and some of them presented an apocrine-like appearance and had cytoplasmic PAS-positive/diastase-resistant granules and hemosiderin. Other cells had foamy cytoplasm with microvacuoles. Immunohistochemistry revealed that the almost all of the tumor cells were strongly positive for S-100. These histological findings suggest the possibility that ANOS might arise secondarily from LGCCA. This is an interesting case regarding the association between ANOS and LGCCA in oncogenesis.Virtual SlidesThe virtual slide(s) for this article can be found here: http://www.diagnosticpathology.diagnomx.eu/vs/1226764594634693.
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