RESUMO
To date, systemic amyloidosis is diagnosed histologically in vitro using Congo red staining or in vivo using iodine-123 serum amyloid P component (123I-SAP) scintigraphy. 99Tcm-labelled derivatives of chrysamine G (CG), a lipophilic analogue of Congo red, were synthesized as potential tracer agents for direct and quantitative scintigraphic evaluation of amyloid deposits. To determine the affinity of 99Tcm-MAMA-CG, 99Tcm-Me4MAMA-CG and 99Tcm-MAMA-CG diethyl ester for amyloid, in vitro autoradiography was performed on sections of human kidney biopsy cylinders from kidneys with amyloid deposits (types AA, Alambda and Akappa) or control kidney tissue after incubation with the respective tracer agents. The binding of 99Tcm-MAMA-CG and its tetramethyl derivative was higher to kidney biopsy material with amyloid deposits of the AA, Alambda or Akappa type compared with control kidney tissue. This higher binding was prevented by the presence of 10 microM Congo red in the incubation medium. The diethyl ester of 9Tcm-MAMA-CG did not demonstrate increased binding to Congo red-positive kidney tissue. In conclusion, 99Tcm-MAMA-CG and 99Tcm-Me4MAMA-CG localize specifically to amyloid deposits in human kidney tissue, suggesting that these tracer agents may be applicable as specific targeting agents for diagnostic purposes in clinical amyloidosis.
Assuntos
Amiloide/análise , Amiloidose/diagnóstico por imagem , Benzoatos , Nefropatias/diagnóstico por imagem , Rim/diagnóstico por imagem , Compostos de Organotecnécio , Compostos Radiofarmacêuticos , Tecnécio , Adulto , Idoso , Autorradiografia , Criança , Feminino , Humanos , Rim/patologia , Masculino , Pessoa de Meia-Idade , Cintilografia , Compostos Radiofarmacêuticos/síntese química , Compostos Radiofarmacêuticos/farmacocinética , Valores de Referência , Tecnécio/farmacocinéticaRESUMO
The early lesions of bilateral diffuse melanocytic proliferation were studied with fluorescein angiography in a 63-year-old woman. We first observed a small choroidal melanoma in the left eye and several flat melanocytic lesions in both eyes. Extension and growth of new melanocytic lesions and leakage at the level of the pigment epithelium were then noted. Subsequently, pink patches, with an eye-catching early hyperfluorescence, appeared in the posterior fundus in both eyes. The patient experienced progressive visual loss during the 8-month follow-up period before her death. Histopathologically, the uveal tracts were diffusely thickened by melanocytic proliferation. The primary systemic neoplasm was an ovarian carcinoma, found in five of 18 patients with this unusual paraneoplastic syndrome.
