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Analysis of parameters such as body weight, lipid profile and blood pressure of 24 middle-aged men reveals favorable effects of energy restriction on human ageing. Body weight and blood pressure decreased and HDL-cholesterol level increased after 10 weeks of energy restriction. There was no detrimental effect on physical and mental ability, hunger and mood.

A study was conducted on retinol internalization from retinol-binding protein (RBP) by hepatic parenchymal cells (PC) in vitro to determine the role of a cell surface RBP receptor in retinol uptake mediation. Results indicate a time-dependent increase in (3H) retinol uptake from (3H)retinol-RBP complex at 37 and 4 degrees centigrade. Retinol uptake was also found to be not saturable at concentrations greater than the physiological concentration by over 3 micromolars and was not inhibited by a 10-fold molar excess of retinol-RBP. Retinol uptake and processing was not found to be dependent on binding with RBP.

The levels of retinoids, retinol-binding protein, cellular retinol-binding protein, cellular retinoic-acid-binding protein, transthyretin and the activities of retinyl palmitate hydrolase and cholesteryl oleate hydrolase were determined in purified parenchymal, fat-storing, endothelial and Kupifer cell preparations, and in liver homogenates from young adult (6-month-old) and old (36-month-old) rats. Retinoid levels were also determined in the plasma from young and old rats. Retinoid contents were determined by H PLC. The binding proteins and transthyretin were measured by specific radioimmunoassays; retinyl palmitate and cholesterol oleate hydrolases were measured by sensitive microassays. The retinoid content of both the liver homogenates and of the fat-storing, and parenchymal cell preparations increased between 6 months and 36 months of age. The cellular distribution of retinoids was similar for the two age groups analyzed with the fat-storing cells being the main retinoid storage sites in the rat liver. Concentrations of retinol-binding protein and transthyretin were high in parenchymal cell preparations. Cellular retinol-binding protein was enriched both in parenchymal and in fat-storing cell preparations; the highest concentrations of cellular retinoic-acid-binding protein were present in fat-storing cell preparations. No major differences were observed between the two age groups in the cellular concentrations and distributions of any of these binding proteins. High activity of cholesterol oleate hydrolase was measured in parenchymal and in Kupifer cell preparations; end othelial cell preparations also contained considerable activities. The distribution of this activity over the various cell types reflects their role in lipoprotein metabolism. Retinyl palmitate hydrolase activity was specifically enriched in parenchymal and in fat-storing cell preparations, consistent with the roles of these cells in retinoid metabolism. No major differences were observed between the two age groups in the cellular distributions of the two hydrolase activities. This study indicates that no major changes occur in the retinoid- related parameters analyzed with age, suggesting that rat liver retinoid metabolism does not change dramatically with age and that retinoid homeostasis is maintained. [ABSTRACT FROM AUTHOR]

The genotoxic effects of intragastrically administered benzo[] pyrene (BaP) were studied in isolated rat liver and intestinal cells. We found that BaP was unable to induce unscheduled DNA synthesis in rat parenchymal liver cells . In contrast, alkaline elution showed that at 5 h after administration of BaP a considerable number of alkali-labile sites was present in the DNA of both intestinal cells and parenchymal liver cells, but not in that of non-parenchymal liver cells. The possibility is discussed that these sites were induced by radical intermediates, generated during the metabolization of BaP. [ABSTRACT FROM PUBLISHER]