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We exploited a necrosis-avid contrast agent ECIV-7 for magnetic resonance imaging (MRI) in rodent liver tumors after radiofrequency ablation (RFA). Rats bearing liver rhabdomyosarcoma (R1) were randomly allocated to three groups: group I, complete RFA, group II, incomplete RFA, and group III, sham ablation. Within 24 h after RFA, T1-weighted (T1-w) MRI was performed before and after injection of ECIV-7 at 0.05 mmol/kg and followed up from 6–24 h. Signal intensities (SIs) were measured with relative enhancement (RE) and contrast ratio (CR) calculated. The MRI findings were verified histomorphologically. On plain T1-w MRI the contrasts between normal liver, RFA lesion, residual and/or intact tumor were vague. Early after administration of ECIV-7, the liver SI was strongly enhanced (RE=40–50%), leaving the RFA lesion as a hypointense region in groups I and II. At delayed phase, two striking peri-ablational enhancement patterns appeared (RE=90% and CR=1.89%), i.e., “O” type of hyperintense rim in group I and “C” type of incomplete rim in group II. These MRI manifestations could be proven histologically. In this study, tissue components after RFA could be characterized with discernable contrasts by necrosis-avid contrast agent (NACA)-enhanced MRI, especially at delayed phase. This approach may prove useful for defining the ablated area and identifying residual tumor after RFA. [ABSTRACT FROM AUTHOR]

Phytoestrogen isoflavones (IFs) are considered to suppress estrogen-related cancers through their antiestrogenic activity. The antioxidant effect of IFs, however, has not been confirmed in an in vivo system, so suppression of hydroperoxide formation and resultant DNA adduct formation were studied. The antioxidant effects of the soya-hypocotyl tea (SHT), which contained daidzein (14+/−1.5 mg/l) and genistein (3+/−0.5 mg/l), were examined in Wistar rats fed the AIN-76 control diet or iron deficient diet (FeD) for 4 weeks. The intake amount of the diet and IFs were measured daily. Urinary excretion of IFs was measured for 3 days before sacrifice. In addition to the serum lipid analyses, phosphatidylcholine hydroperoxide (PCOOH), and phosphatidylethanolamine hydroperoxide (PEOOH) production in red blood cells and the liver were measured as a biomarker of oxidants. Production of DNA adducts by oxidative stress was measured by the amount of 8-hydroxy-2′-deoxyguanosine (oh8dG) in the liver and kidney, and urine. Histological changes were checked by H&E staining and immunohistochemistry for oh8dG. FeD rats showed anemia, growth retardation, hyperlipidemia. IFs only lowered the triacylglycerol level and did not change the cholesterol level. Rats fed the normal diet did not show suppression of PCOOH and PEOOH production in either red blood cells or the liver, while groups administered SHT showed suppressed production of PCOOH and PEOOH in the liver. The cumulative intake of daidzein, genistein and the total amount of IFs showed significant inverse associations with urinary excretion of oh8dG. oh8dG in the kidney showed an inverse association with the amount of oh8dG in the urine. Enzymehistochemically, a strong localization of oh8dG was found in the epithelial cells of the bile canaliculi and proximal tubules of the kidney. IFs and SHT showed antioxidant effects at physiological concentrations in an in vivo system. The antioxidant effects of IFs decreased oxidation stress to the nuclear DNA, which was shown by the decreased oh8dG production. It is suggested that to prevent various cancers, in addition to the known antiestrogenie, antityrosin kinase, and other effects. IFs appeared to promote excretion of oh8dG. [ABSTRACT FROM AUTHOR]