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Transgenic mice overexpressing human apolipoprotein A-II (huapoA-II) display high VLDL and low HDL levels. To evaluate the antioxidant potential of huapoA-II enriched HDL, we measured the activities of paraoxonase (PON) and platelet-activating factor acetylhydrolase (PAF-AH). Both activities decreased up to 43% in the serum of transgenic mice compared with controls, varied in parallel to HDL levels, but decreased less than HDL levels. The major part of PON and PAF-AH was associated with HDL, except in fed high huapoA-II-expressing mice, in which 20% of PAF-AH and 9% of PON activities were associated with VLDL. PON mRNA levels in the liver, its major site of synthesis, were similar in transgenic and control animals, indicating normal enzyme synthesis. In transgenic mice, the basal oxidation of lipoproteins was not increased, whereas their VLDL were more susceptible to oxidation than VLDL of controls. Interestingly, HDL of transgenic mice protected VLDL from oxidation more efficiently than HDL of controls. In conclusion, the decrease in both PON and PAF-AH activities in huapoA-II transgenic mice is best explained by their lower plasma HDL levels. However, the unchanged basal lipoprotein oxidation in transgenic mice suggests that huapoA-II-rich HDL may maintain adequate antioxidant potential.—Boisfer, E., D. Stengel, D. Pastier, P. M. Laplaud, N. Dousset, E. Ninio, and A-D. Kalopissis. Antioxidant properties of HDL in transgenic mice overexpressing human apolipoprotein A-II. J. Lipid Res. 2002. 43: 732–741.

Male New Zealand white rabbits were whole-body-irradiated with a linear electron accelerator at 800 rad ( LD50 in 30 days). This treatment induced a pronounced hypertriglyceridemia. The apoprotein composition of very low density lipoproteins (VLDL, d < 1.006 g/ml) and high-density lipoproteins (HDL, d = 1.063-1.21 g/ml) from irradiated rabbits was studied and compared to those of normal rabbits. Significant changes were observed in both very low density apolipoproteins and high-density apolipoproteins. (1) In the VLDL fraction from irradiated rabbits, there appeared in high proportion two apolipoproteins with electrophoretic mobility in urea/polyacrylamide gels similar to apoA-I and A-II but which were distinctly different in their apparent molecular weights, their isoelectric points, and their amino acid composition from these latter proteins. These proteins had apparent molecular weights of about 10,000. They focused into three bands with pI values of 6.1, 6.4, and 6.6. Their amino acid composition was ...