Effect of free fatty acids and cholesterol in vitro on liver plasma membrane-bound enzymes

1982 ◽  
Vol 38 (1) ◽  
pp. 102-104 ◽  
Author(s):  
S. Leoni ◽  
P. Luly ◽  
M. T. Mangiantini ◽  
S. Spagnuolo
Keyword(s):  
Fatty Acids ◽  
Plasma Membrane ◽  
Free Fatty Acids ◽  
Liver Plasma Membrane ◽  
Membrane Bound ◽  
Membrane Bound Enzymes

Effects of ethanol administration on rat liver plasma membrane-bound enzymes

1985 ◽  
Vol 34 (15) ◽  
pp. 2685-2689 ◽  
Author(s):  
Jorge L. Gonzalez-Calvin ◽  
John B. Saunders ◽  
Ian R. Crossley ◽  
Christopher J. Dickenson ◽  
Heather M. Smith ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Rat Liver ◽  
Ethanol Administration ◽  
Liver Plasma Membrane ◽  
Membrane Bound ◽  
Membrane Bound Enzymes

Effect of chlorpropamide and phenformin on rat liver: The effect on plasma membrane-bound enzymes and cyclic AMP content of hepatocytes in vitro

1977 ◽  
Vol 46 (2) ◽  
pp. 153-164 ◽  
Author(s):  
Paolo Luly ◽  
Patrizia Baldini ◽  
Carmine Cocco ◽  
Sandra Incerpi ◽  
Eusebio Tria
Keyword(s):  
Plasma Membrane ◽  
Cyclic Amp ◽  
Rat Liver ◽  
Membrane Bound ◽  
Membrane Bound Enzymes

scholarly journals A novel adenylylation process in liver plasma membrane-bound proteins

1990 ◽  
Vol 265 (33) ◽  
pp. 20653-20661
Author(s):  
E San José ◽  
A Benguría ◽  
A Villalobo
Keyword(s):  
Plasma Membrane ◽  
Liver Plasma Membrane ◽  
Membrane Bound

Free fatty acids normalize a rosiglitazone-induced visfatin release

2006 ◽  
Vol 291 (5) ◽  
pp. E885-E890 ◽  
Author(s):  
Dominik G. Haider ◽  
Friedrich Mittermayer ◽  
Georg Schaller ◽  
Michaela Artwohl ◽  
Sabina M. Baumgartner-Parzer ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Term Treatment ◽  
Double Blind ◽  
Lipid Infusion ◽  
Major Mechanism ◽  
Insulin Mimetic ◽  
Long Term Treatment ◽  
Plasma Ffa

The detrimental effect of elevated free fatty acids (FFAs) on insulin sensitivity can be improved by thiazolidinediones (TZDs) in patients with type 2 diabetes mellitus. It is unknown whether this salutary action of TZD is associated with altered release of the insulin-mimetic adipocytokine visfatin. In this study, we investigated whether visfatin concentrations are altered by FFA and TZD treatment. In a randomized, double-blind, placebo-controlled, parallel-group study 16 healthy volunteers received an infusion of triglycerides/heparin to increase plasma FFA after 3 wk of treatment with rosiglitazone (8 mg/day, n = 8) or placebo ( n = 8), and circulating plasma visfatin was measured. As a corollary, human adipocytes were incubated with synthetic fatty acids and rosiglitazone to assess visfatin release in vitro. The results were that rosiglitazone treatment increased systemic plasma visfatin concentrations from 0.6 ± 0.1 to 1.7 ± 0.2 ng/ml ( P < 0.01). Lipid infusion caused a marked elevation of plasma FFA but had no effect on circulating visfatin in controls. In contrast, elevated visfatin concentrations in subjects receiving rosiglitazone were normalized by lipid infusion. In isolated adipocytes, visfatin was released into supernatant medium by acute addition and long-term treatment of rosiglitazone. This secretion was blocked by synthetic fatty acids and by inhibition of phosphatidylinositol 3-kinase or Akt. In conclusion, release of the insulin-mimetic visfatin may represent a major mechanism of metabolic TZD action. The presence of FFA antagonizes this action, which may have implications for visfatin bioactivity.

Lipid Labelling in Intact Chloroplasts from Exogenous Nucleotide Precursors

1981 ◽  
Vol 36 (1-2) ◽  
pp. 62-70 ◽  
Author(s):  
Margrit Bertrams ◽  
Käthe Wrage ◽  
Ernst Heinz
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
De Novo ◽  
Membrane System ◽  
Chloroplast Envelope ◽  
Label Free ◽  
Intact Chloroplasts ◽  
Time Required

Abstract De novo-synthesis of glycerolipids in chloroplasts is initiated by a stroma enzyme which catalyzes the formation of lyso-phosphatidic acid from glycerophosphate and acyl-CoA. When these substrates are added to isolated, intact chloroplasts, only glycerophosphate can readily pass through the chloroplast envelope which represents a permeation barrier for acyl-CoA, although higher thioester concentrations destroy this membrane system. At low concentrations of acyl-CoA, which do not impair the envelope, intact chloroplasts metabolize exogenous acyl-CoA in two ways to give free fatty acids and labelled phosphatidyl choline. This indicates that the envelope thioesterase can use exogenous substrates. Isolated, intact chloroplasts fixing radioactive CO2 label free fatty acids and acylglycerols but not galactolipids, since they cannot convert 3-phosphoglycerate into UDP-galactose which in vivo is supplied by the cytoplasm. This cooperation was simulated in vitro by adding all enzymes and cofactors necessary for conversion of 3-phosphoglycerate into UDP-galactose to intact chloro­plasts which then formed labelled monogalactosyl diacylglycerol from labelled CO2. The time required to transfer envelope-made galactolipids from the envelope into thylakoids was studied by incubating intact chloroplasts with radioactive UDP-galactose, subsequent osmotic disruption of organelles with concomitant enzymatic degradation of UDP-galactose followed by separation of envelopes and thylakoids. Only after short times (< 1min) appreciable proportions 920-30%) of radioactive galactolipid export from envelopes into thylakoids.

scholarly journals ULTRASTRUCTURAL STUDY OF MEMBRANE-BOUND ENZYMES IN THYMOCYTES

1974 ◽  
Vol 22 (12) ◽  
pp. 1128-1134 ◽  
Author(s):  
ARIANE MONNERON ◽  
JEAN-CLAUDE BENICHOU ◽  
INSTITUT PASTEUR ◽  
YVETTE FLORENTIN ◽  
ELIANE GUERRY
Keyword(s):  
Plasma Membrane ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Uridine Diphosphate ◽  
Lead Phosphate ◽  
Isolated Nuclei ◽  
Whole Cells ◽  
Diphosphate Glucose ◽  
Membrane Bound ◽  
Membrane Bound Enzymes ◽  
Phosphate Deposits

Calf thymocytes in suspension, as well as isolated calf thymocyte nuclei, were incubated in the presence of several phosphorylated substrates. 5'-Nucleotidase was easily detected on the plasma membrane of thymocytes (external side), but could be demonstrated on isolated nuclei only to a small extent. No other substrates were detectably hydrolyzed by isolated nuclei except adenosine triphosphate and 3'-thymidine monophosphate. The surface of whole cells was found to be much more reactive. A 3'-nucleotidase activity was shown to occur on the plasma membrane of a number of thymocytes and produced large lead phosphate deposits, some of them protruding into the cytoplasm. Enzymic activities splitting β-nicotinamide adenine dinucleotide phosphate and uridine diphosphate glucose were also readily detectable on the surface of cells. Since the pattern of the lead phosphate deposits and the number of reactive cells varied with the added substrate, and since cells were compared with their isolated nuclei, the positive reactions were considered to indicate the presence (on the exposed membranes) of the corresponding enzymes on the exposed membranes.

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