RESUMO
We herein report that the clinical, laboratory, and radiographic features and positron emission tomography (PET) imaging may provide valuable clues to the pathogenesis of cerebral amyloid angiopathy (CAA)-associated encephalopathy, which currently remains unclear. We herein describe two cases of encephalopathy with CAA, with an emphasis on PET imaging with (11)C-Pittsburgh compound B ((11)C-PiB) and (18)F-fluorodeoxyglucose ((18)F-FDG). One case of Alzheimer's disease for which a brain biopsy was performed showed CAA-related inflammation. Another case that had developed sudden sensory aphasia presented with posterior reversible encephalopathy syndrome-like vasogenic edema in the left temporal region with (11)C-PiB uptake and microhemorrhages. (11)C-PiB and (18)F-FDG PET are useful for detecting CAA-associated encephalopathy, including atypical CAA cases.
Assuntos
Benzotiazóis , Angiopatia Amiloide Cerebral/diagnóstico por imagem , Tomografia por Emissão de Pósitrons/métodos , Síndrome da Leucoencefalopatia Posterior/diagnóstico por imagem , Idoso , Compostos de Anilina , Radioisótopos de Carbono , Angiopatia Amiloide Cerebral/complicações , Diagnóstico Diferencial , Humanos , Masculino , Síndrome da Leucoencefalopatia Posterior/etiologia , TiazóisRESUMO
The reaction catalyzed by adenosylcobalamin-dependent diol dehydratase proceeds by a radical mechanism. A radical pair consisting of the Co(II) of cob(II)alamin and an organic radical intermediate formed during catalysis gives EPR spectra. The high-field doublet and the low-field broad signals arise from the weak interaction of an organic radical with the low-spin Co(II) of cob(II)alamin. To characterize the organic radical intermediate in the diol dehydratase reaction, several deuterated and (13)C-labeled 1,2-propanediols were synthesized, and the EPR spectra observed in the catalysis were measured using them as substrate. The EPR spectra with the substrates deuterated on C1 showed significant line width narrowing of the doublet signal. A distinct change in the hyperfine coupling was seen with [1-(13)C]-1,2-propanediol, but not with the [2-(13)C]-counterpart. Thus, the organic radical intermediate observed by EPR spectroscopy was identified as the 1,2-propanediol-1-yl radical, a C1-centered substrate-derived radical.