We plan to investigate the effects of stearic acid, arachidonic acid, 22:6n3 and other C20-unsaturated fatty acids on fatty acid synthesis and lipogenesis in isolated hepatocytes. This will include kinetics of incorporation of 14C-acetate, other 14C-labeled substrates and 3H2O into fatty acids in different lipid classes and into individual fatty acids. Incorporation of glycerol will also be tested. We plan also to measure in vivo liver lipogenesis as measured by 3H2O incorporation into fatty acids after feeding or infusing fatty acids. We plan to continue studying the physical properties of synthetic lecithins. Observations of pressure-area curves and sterol/PC interactions will be extended to include PC molecules containing fatty acids with chain lengths ranging from 12 to 24 carbon atoms. Synthetic PC and PC/sterol mixtures will also be examined with differential scanning calorimetry to verify monolayer measurements, especially the observation that fully saturated PC differ from unsaturated PC in exhibiting maximum interaction at a high molar % of PC.