The effect of dietary conjugated linoleic acid (CLA) on hepatic lipid parameters in Sprague-Dawley rats was examined. When rats were fed a diet containing CLA at 0 (control), 1, or 2% of the weight of the amount of food given for 3 weeks, the liver weight exhibited a slight increase in the CLA-fed groups, although the difference was not significant. Lipid accumulation in the hepatocytes of CLA-fed rats was also demonstrated by electron microscopic observation. In addition, the liver thiobarbituric acid reactive substances levels were significantly higher in the 2 wt % CLA group than in the other two dietary groups, and the levels of phosphatidylcholine hydroperoxide were higher in CLA-fed groups when compared to that of the control group. On the other hand, the serum lipid peroxide levels were comparable among all three dietary groups. Levels of triglycerides in the white adipose tissue (WAT) and serum nonesterified fatty acid (NEFA) were reduced in a CLA-dose-dependent manner. CLA was shown to accumulate in the WAT much more than in the serum or liver. These results suggest that CLA accelerates the decomposition of storage lipids in WAT and the clearance of serum NEFA levels, resulting in lipid peroxidation and a morphological change in the liver.

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Block and random copolypeptides of r-benzyl L-glutamate and Lalanine of narrow molecular weight distribution were synthesized by successive polymerization of the corresponding N-carboxy a-amino acid anhydrides with initiation by n-butylamine. Optical rotatory dispersion data show that the copolypeptides studied are essentially a-helical in m-cresol in a temperature range between 10 and 50°C. Dielectric dispersion and viscosity data for m-cresol solutions indicate that the copolypeptides have a rodlike molecular shape. The dielectric dispersion data in m-cresol as a function of copolymer composition gave 6.4±0.1 D for the monomeric dipole moment of L-alanine residue. This value is larger than those reported for other polypeptides with polar side chains, and suggests that the side chain dipoles on the average run antiparallel to the backbone dipoles. For polypeptides with polar side chains, the monomeric dipole moment was found to increase with the length of the side chain. This is ascribed to the increased rotational freedom of the longer side chain, which tends to reduce the side chain contribution to the total dipole moment.