An 11-year-old Shih Tzu presented with crusting and erythema, mainly on the abdomen and the root of the tail. Based on histopathological findings, blood examinations and necropsy findings, the condition was diagnosed as superficial necrolytic dermatitis associated with a glucagon-secreting extrapancreatic neuroendocrine tumour. Gross necropsy revealed tumour invasion into the spleen, liver, adrenal glands and mesenteric lymph nodes. Immunohistochemical analysis of the neoplastic cells revealed that the tumour was a glucagonoma, consistent with earlier findings of persistent glucagonaemia and hypoaminoacidaemia.
A monospecific and high titer polyclonal antibody, designated as Fas D, raised against synthetic polypeptides selected from a part of the human Fas antigen (aa 104-114), was used to identify the Fas antigen in human oral epithelia in normal and pathological states. The human gingival proteins had been extracted and analysed by an ABC (avidin-biotin complex) immunoblotting technique. The antibody interacted with a single band in gingival proteins with an estimated molecular weight of 35,000, which is in good agreement with that calculated from amino acid sequences of the human Fas antigen. Using an indirect immunohistochemical method, the antibody localized on the stratum spinosum and the basal part of the stratum corneum of normal human gingiva. Specimens obtained from patients with odontogenic keratocysts, leukoplakia, lichen planus, and squamous cell carcinoma were also stained with the antibody. The pattern of the Fas antigen distribution in oral stratified squamous epithelia was, with some overlapping, characteristic for each disease.
The Fas antigen is a cell-surface glycoprotein that mediates apoptosis from the cell surface into the cytoplasm. Polyclonal antibody (Fas D) was raised against a synthetic polypeptide selected from the extracellular part of the human Fas antigen (amino acid residues 104-114) and was used to detect the Fas antigen in human gingiva. Biopsy specimens of human gingiva were prepared, and the paraffin sections were reacted with the Fas D antibody by an immunohistochemical method. The antibody localized to the prickle-cell layer and to granular layer keratinocytes of human gingiva. Proteins were also prepared from human gingiva and subjected to SDS-PAGE, followed by Western-blotting analysis with the Fas D antibody. The antibody interacted with a band corresponding to an estimated molecular weight of 35 kDa. The incidence of the immunoreactive 35-kDa protein was detected in the gingiva of 90% of the 20 individuals examined. The Fas antigen detected in human gingiva may be related to the physiological turnover of oral mucosa.
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