The limiting step of fat synthesis is fatty acid synthesis, in which the lipogenic enzymes (acetylCoA carboxylase, fatty acid synthase, ATP-citrate lyase, malic enzyme and glucose-6-phosphate dehydrogenase) are involved. The recent advances made in the study of regulation of lipogenic enzyme gene expression in rat liver are summarized here, with reference to our results. Aspects covered by this review are : 1) time courses of changes in the gene expression after feeding a high-carbohydrate diet; 2) effects of diet quantity on gene expression; 3) effects of dietary nutrients on gene expression; 4) effects of insulin, triiodothyronine and fructose on gene expression.
We studied the effects of dietary fiber polydextrose feeding on plasma lipids and changes in diurnal plasma sugar, insulin and blood pressure levels. Seventeen patients were entered into the study. Polydextrose (15g/day) was given to the subjects for 4 weeks. Plasma total cholesterol (TC) and lowdextrose (15g/day) was given to the subjects for 4 weeks. Plasma total cholesterol (TC) and lowdensity lipoprotein cholesterol (LDL-C) levels were reduced by 6% by polydextrose, but these changes were not significant. Plasma apo (protein) B concentrations were significantly decreased (p<0.05). Polydextrose did not affect the diurnal changes in plasma sugar levels, but significantly decreased the level of plasma insulin at 2h after dinner (p<0.02) and at midnight (p<0.05), respectively. In mildly hypertensive patients, the systolic blood pressure between 12: 00 and 18: 00h and the diastolic blood pressure between 18: 00 and 24: 00h were significantly decreased, respectively (p<0.05, p<0.05). Urinary Na/K excretion ratio was slightly increased by polydextrose. The effects of polydextrose on blood pressure seemed to be related to the decrease in plasma insulin levels.
A protease inhibitor (PEPI) was isolated and purified from the juice of the passion fruit (Passiflora edulis Sim) by DEAE-Sephacel and trypsin-Sepharose 4B column chromatography. The molecular weight of PEPI was found to be 25 kDa by gel filtration. PEPI exhibited a single band in native and SDSPAGE gels under non-reducing conditions. Under reducing conditions in SDS-PAGE gel, PEPI exhibited three protein bands with estimated molecular weights of 25, 22, 18 kDa, respectively. The three protein bands were stained with PAS reagent. PEPI inhibited trypsin and chymotrypsin activities, but did not inhibit papain activity. The trypsin-inhibitory activity of PEPI was heat-stable, retaining 50% of the original activity even after exposure to 100°C for 10 min. The trypsin-inhibitory activity of PEPI was stable over a pH range of 2-12.