Assuntos
Carcinoma de Células Renais/diagnóstico por imagem , Carcinoma de Células Renais/secundário , Neoplasias Cardíacas/diagnóstico por imagem , Neoplasias Cardíacas/secundário , Ventrículos do Coração , Neoplasias Renais/patologia , Tomografia Computadorizada por Raios X , Técnicas de Imagem Cardíaca , Feminino , Humanos , Pessoa de Meia-Idade , Imagem Radiográfica a Partir de Emissão de Duplo Fóton , Tomografia Computadorizada por Raios X/métodosRESUMO
Aqueous solutions of linoleic acid were irradiated in air with gamma-rays of 137Cs. High pressure liquid chromatography (HPLC) was been used to separate and measure the production of hydroperoxides. The results obtained after reverse phase chromatography, associated with a microperoxydase for hydroperoxide detection, indicate the presence of two different hydroperoxides. One type of hydroperoxide was the major product obtained when the initial linoleic concentrations were below the critical micellar concentration (2 mM), and the second type was produced when the concentrations were above 2 mM. A further separation carried out on the second hydroperoxide by direct phase HPLC showed that it contains three compounds, mainly HPODE 9 and 13.
Assuntos
Ácidos Graxos Insaturados/química , Ácidos Graxos Insaturados/efeitos da radiação , Peroxidação de Lipídeos/efeitos da radiação , Peróxidos Lipídicos/química , Peróxidos Lipídicos/efeitos da radiação , Cromatografia Líquida de Alta Pressão , Raios gama , Ácido Linoleico/química , Ácido Linoleico/efeitos da radiação , Peróxidos Lipídicos/análise , Medições Luminescentes , Espectrofotometria UltravioletaRESUMO
Peroxidation of unconjugated polyunsaturated fatty acids such as linolenic acid proceeds through a free radical chain mechanism and is accompanied by the formation of conjugated dienes such as hydroperoxides. In an investigation of radiation-induced oxidation of aqueous linolenate, we have measured two indexes of peroxidation: (1) conjugated dienes by means of absorption spectroscopy and (2) hydroperoxides by high-pressure liquid chromatography using detection of chemiluminescence. The experimental results indicate a strong effect of the concentration of linolenate on the yields of oxidized products. In addition, this work shows the quantitative production of two kinds of hydroperoxides. The ratio of these hydroperoxides is independent of the radiation dose but is dependent on the linolenate concentration. One hydroperoxide is formed predominantly below the critical micellar concentration (3 mM under our conditions), while the second is observed predominantly when micelles are formed in the aqueous medium. The influence of the composition of the medium on the nature of both hydroperoxides is discussed. [bj163]
Assuntos
Peróxido de Hidrogênio/síntese química , Ácido gama-Linolênico/efeitos da radiação , Cromatografia Líquida de Alta Pressão , Relação Dose-Resposta à Radiação , Peróxido de Hidrogênio/análise , Medições Luminescentes , Micelas , Soluções , Ácido gama-Linolênico/químicaRESUMO
Peroxidation of polyunsaturated fatty acids such as linoleic acid in aqueous micellar solution proceeds through a free-radical chain mechanism and is accompanied by the formation of conjugated dienes, some in the form of hydroperoxides. In the course of an investigation of radiation-induced oxidation of aqueous sodium linoleate, we have measured three indexes of peroxidation-conjugated dienes, hydroperoxides and thiobarbituric acid-reactive substances-by means of absorption spectroscopy, high-pressure liquid chromatography and spectrofluorimetry, respectively. There are linear correlations between the amounts of conjugated dienes, hydroperoxides and thiobarbituric acid-reactive substances. The radiolytic yields have been determined from the radiation dose dependence of the three markers of peroxidation as a function of sodium linoleate concentration. The results obtained indicate a strong effect of the concentrations of oxygen and linoleate on the yields of the products. The yields at different lipid concentrations display a large increase in chain propagation length; this is discussed in terms of the effect of micellar size.