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Sterol regulatory element-binding protein (SREBP)-1a is a key transcription factor that activates the expression of genes involved in the synthesis of fatty acids, triglycerides (TGs), and cholesterol. Transgenic mice that overexpress the nuclear form of SREBP-1a under the control of the phosphoenolpyruvate carboxykinase promoter (Tg-1a) were previously shown to display a lipodystrophic phenotype characterized by enlarged and fatty livers, diminished peripheral white adipose tissue (WAT), and insulin resistance. In the current study, we crossed these Tg-1a mice with genetically obese (ob/ob) mice (Tg-1a;ob/ob) and examined change in fat distribution between liver and adipose tissues in severe obesity and mechanism underlying the lipodystrophic phenotype in mice with Tg-1a. Tg-1a;ob/ob mice developed more severe steatohepatitis but had reduced WAT mass and body weight compared with ob/ob mice. The reduction of WAT mass in Tg-1a and Tg-1a;ob/ob mice was accompanied by enhanced lipogenesis and lipid uptake in the liver, reduced plasma lipid levels, impaired adipocyte differentiation, reduced food intake, enhanced energy expenditure, and extended macrophage infiltration and fibrosis in WAT. Despite the improved glucose tolerance, Tg-1a;ob/ob mice showed severe peripheral insulin resistance. Adenoviral hepatic expression of SREBP-1a mimicked these phenotypes. The "fat steal"-like lipodystrophy phenotype of the Tg-1a;ob/ob model demonstrates that hepatic SREBP-1a activation has a strong impact on the partition of TG accumulation, resulting in adipose-tissue remodeling by inflammation and fibrosis and insulin resistance.

The adhesion and corrosion performances for several pretreatments of 55% Al-Zn-coated steels which were coil-coated with polyester paint systems were determined. The objective of this study was to evaluate new, silane-based metal pretreatments and to compare their performance with the conventional pretreatments based on chromates and with other non-chromate metal pretreatments such as Zr-based treatments. The silanes used were y-aminopropyltriethoxysilane, styrylaminoethylaminopropyltrimethoxysilane, and bis-(triethoxysilyl)ethanesilane. In the comparison of the pretreatment performances, the standard chromate anticorrosive paint pigment was replaced with an ion exchange pigment. The painted panels were tested for adhesion by a 90° paint pull-off test and by a crosshatch test. Corrosion rates were determined by electrochemical impedance spectroscopy (EIS) and by accelerated tests: salt spray, GM Scab, Cleveland, and the new Volvo indoor test. The results indicate that silanes are comparable to the standard chromate in terms of paint adhesion and corrosion protection, but the silane performance is dependent on the metal cleaning process. Further, the ranking of all treatments studied varied in the different tests that were compared. None of the systems studied matched the performance of the standard paint system with a chromate anticorrosion pigment, indicating that the effect of an anticorrosion pigment in determining the rate of corrosion propagation in a painted panel is much greater than that of the metal pretreatment. A model is presented which explains the mechanism controlling the edge corrosion behaviour of painted 55% Al-Zn-coated steel and the relative effects of metal pretreatment and paint pigment on the overall corrosion protection. This model is based on cross-sectional analyses by SEM/EDX of painted panels after exposure in the Volvo test.

Various coated metal samples with different pretreatments were investigated by electrochemical impedance spectroscopy (EIS). Variables were the substrate (cold-rolled steel and hot-dipped galvanized steel), phosphate system (iron and zinc phosphate), post rinse (chromate and silane/zirconium rinse) and paint systems. The corrosion performance was determined on the basis of coating degradation, water uptake and interface delamination of the tested samples. The zinc phosphate performed better than iron phosphate on CRS. The silane/Zr rinse did not perform well in the CRS/iron-phosphate system. However, it showed a better performance than the chromate when used as a post rinse of zinc phosphate. Salt spray test (SST) and adhesion test results of the same samples are also reported in this paper and compared to the EIS data. The correlation among three test methods was poor.