Assuntos
Pustulose Exantematosa Aguda Generalizada/etiologia , Meios de Contraste/efeitos adversos , Iohexol/análogos & derivados , Iopamidol/análogos & derivados , Pustulose Exantematosa Aguda Generalizada/patologia , Pustulose Exantematosa Aguda Generalizada/prevenção & controle , Corticosteroides/uso terapêutico , Idoso de 80 Anos ou mais , Reações Cruzadas , Humanos , Iohexol/efeitos adversos , Iopamidol/efeitos adversos , Masculino , Testes do Emplastro , Pré-Medicação , Índice de Gravidade de DoençaRESUMO
Seawater is constantly circulating through oceanic basement as a low-temperature hydrothermal fluid (<150 degrees C). In cases when ultramafic rocks are exposed to the fluids, for instance during the initial phase of subduction, ferromagnesian minerals are altered in contact with the water, leading to high pH and formation of secondary magnesium hydroxide, among other--brucite, that may scavenge borate and phosphate from seawater. The high pH may promote abiotic formation of pentoses, particularly ribose. Pentoses are stabilized by borate, since cyclic pentoses form a less reactive complex with borate. Analyses have shown that borate occupies the 2' and 3' positions of ribose, thus leaving the 5' position available for reactions like phosphorylation. The purine coding elements (adenine, in particular) of RNA may be formed in the same general hydrothermal environments of the seafloor.