Extract from the brain of young mice produced weak cytoproliferative effect on cultured glial cells, while brain extract from old mice 3-4- and 30-60-fold stimulated glial proliferation in primary ...and passaged cell cultures, respectively.PUBLICATION ABSTRACT
The interrelationship between very low density lipoprotein (VLDL) secretion and bile acid production was studied in primary culture of rabbit hepatocytes. Chylomicron remnants (CR) were added to the ...cultures to study their effect on VLDL secretion and bile acid production. After 24 hr preincubation of cells with CR (10-50 micrograms protein/mL), intercellular neutral lipid content was increased 1.5-4-fold in a dose-dependent manner. Neutral lipid accumulation was accompanied by a 70-90% reduction of 14Cacetate incorporation into cholesterol, while no stimulation of 14Coleate incorporation into cholesteryl esters was observed. Incubation of cells with CR increased secretion of free cholesterol, triacylglycerol and apoproteins B and E in VLDL. Stimulation of VLDL cholesterol secretion was accompanied by a reduction of taurocholic acid synthesis. These data demonstrate the existence of an inverse relationship between secretion of VLDL cholesterol and bile acid production under conditions of effective uptake of triacylglycerol-rich CR by hepatocytes.
The main objectives of this study were to compare the effects of dietary commercial cholesterol (containing 5% of oxidized cholesterol derivatives) and purified cholesterol on the secretion rate of ...very low density lipoprotein apolipoproteins and lipids by cultured rabbit hepatocytes and to verify the hypothesis that products of cholesterol autoxidation stimulate the rapid development of hypercholesterolemia. Rabbits fed dietary (old) commercial cholesterol for six weeks showed a fivefold increase in the serum concentration of cholesterol compared with that in purified cholesterol-fed rabbits. The secretion rates of very low density lipoprotein total protein and very low density lipoprotein 3Hapolipoproteins were similar for the hepatocytes of these two cholesterol-fed groups of animals and were two- and threefold greater, respectively, than for cells from control rabbits. Cholesteryl ester content of the hepatocytes from dietary (old) commercial cholesterol-fed rabbits was dramatically increased in comparison with hepatocytes from control and purified cholesterol-fed rabbits. The elevated intracellular cholesteryl ester content is assumed to account for such an increase of very low density lipoprotein-cholesteryl ester secretion by cells prepared from dietary (old) commercial cholesterol-fed rabbits. These effects appear to be caused by activation of cholesterol esterification by oxidized cholesterol derivatives. The rapid development of hypercholesterolemia induced by dietary (old) commercial cholesterol is associated, at least in part, with the stimulated production of hepatic very low density lipoprotein apolipoproteins and cholesteryl esters.
We report the first observation of the Cabibbo-suppressed charm baryon decay Ξ_{c}^{+}→pK^{-}π^{+}. We observe 150±22±5 events for the signal. The data were accumulated using the SELEX spectrometer ...during the 1996-1997 fixed target run at Fermilab, chiefly from a 600 GeV/c Σ^{-} beam. The branching fractions of the decay relative to the Cabibbo-favored Ξ_{c}^{+}→Σ^{+}K^{-}π^{+} and Ξ_{c}^{+}→Ξ^{-}π^{+}π^{+} are measured to be B(Ξ_{c}^{+}→pK^{-}π^{+})/B(Ξ_{c}^{+}→Σ^{+}K^{-}π^{+})=0.22±0.06±0.03 and B(Ξ_{c}^{+}→pK^{-}π^{+})/B(Ξ_{c}^{+}→Ξ^{-}π^{+}π^{+})=0.20±0.04±0.02, respectively.
The secretion of newly synthesized very low density lipoprotein and low density lipoprotein (VLDL + LDL) and high density lipoprotein (HDL) in cultured human hepatocytes in the presence or absence of ...bezafibrate added to the culture medium has been evaluated. The content of triacylglycerol, apolipoprotein B, 3H-labeled proteins and 14C-labeled lipids accumulated in a culture medium increased linearly for periods up to 18 h. During incubation, cellular triacylglycerol content was unchanged. This hypolipidemic agent, at a concentration of 10 microM, inhibited secretion of the several VLDL + LDL 3Hapolipoproteins and the VLDL + LDL 14Clipids, suggesting it can affect the processes of biosynthesis and secretion. The secretion of total 3Hapolipoproteins in the HDL fraction and 3Hprotein (d greater than 1.21 g/ml) was unchanged after an exposure to bezafibrate (10 microM). Incubation in the presence of 10 microM bezafibrate resulted also in decreases in both total VLDL neutral lipids and apolipoprotein B secreted into the medium. These results indicate that bezafibrate might exert its plasma lipid-lowering effect by suppressing the VLDL production in liver and reducing the secretion of VLDL into the circulation.
PDF
