Search results for "Retinyl palmitate"
showing 8 items of 8 documents
Familial hypobetalipoproteinemia due to apolipoprotein B R463W mutation causes intestinal fat accumulation and low postprandial lipemia
2008
Abstract Objective Familial hypobetalipoproteinemia (FHBL) is characterized by inherited low plasma levels of apolipoprotein B (apoB)-containing lipoproteins. In this paper we investigated whether the already described APOB R463W missense mutation, a FHBL mutation able to impair the activity of microsomal triglyceride transfer protein (MTP), may cause intestinal fat accumulation and reduced postprandial lipemia. Methods Four out of five probands harboring APOB R463W mutation were compared with six healthy controls and six patients with celiac disease (CD). An oral fat load supplemented with retinyl palmitate (RP) was administered and a gastro-duodenal endoscopy with biopsy was performed. Re…
Normal intestinal dietary fat and cholesterol absorption, intestinal apolipoprotein B (ApoB) mRNA levels, and ApoB-48 synthesis in a hypobetalipoprot…
1997
Abstract The purpose of this study was to characterize intestinal apolipoprotein B (apoB) metabolism in subjects with familial hypobetalipoproteinemia (FHBL), where segregation analysis supports linkage to the apoB gene but no apoB truncations are present. We investigated cholesterol and fat absorption, intestinal apoB mRNA synthesis and editing, as well as apoB-48 synthesis. Plasma triglycerides (TG) and retinyl palmitate in the chylomicron fractions were analyzed after 12 hours of fasting and then repeatedly for 14 hours after ingestion of a vitamin A—containing high-fat meal. Cholesterol absorption was assessed using a dual stable-isotope method. Mean peak times and concentrations and ar…
Low-density lipoproteins generated during an oral fat load in mild hypertriglyceridemic and healthy subjects are smaller, denser, and have an increas…
2005
Triglyceride-rich lipoproteins generated during the postprandial phase are atherogenic. Large very low-density lipoproteins (LDLs) or chylomicrons (CMs) are not as atherogenic as their remnants (Rem). Small and dense LDLs are associated with cardiovascular disease. Low-density lipoprotein size is partly under genetic control and is considered as a relatively stable LDL feature. In this article, we present data on retinyl palmitate kinetics correlated with the modification of LDL features in terms of size, density, and in vitro receptor binding affinity after an oral fat load. Six nondiabetic, hypertriglyceridemic (HTG) patients and 6 healthy controls were examined. Low-density lipoprotein s…
Antimutagenic effects and possible mechanisms of action of vitamins and related compounds against genotoxic heterocyclic amines from cooked food.
1999
Possible antimutagenic activity of 26 vitamins and related compounds - ascorbic acid, beta-carotene, cyanocobalamin, folic acid, nicotinic acid, nicotinamide, pantothenic acid, pyridoxale, pyridoxamine, pyridoxine, retinal, retinol, retinoic acid, retinyl acetate, retinyl palmitate, riboflavin, riboflavin 5'-phosphate, flavin adenine dinucleotide (FAD), alpha-tocopherol, alpha-tocopherol acetate, vitamins K(1), K(3), K(4), 1, 4-naphthoquinone, and coenzyme Q(10) - was tested against six heterocyclic amine (HCA) mutagens, i.e., 2-amino-3-methyl-imidazo[4, 5-f]quinoline (IQ), 2-amino-3,4-dimethyl-imidazo[4,5-f]quinoline (MeIQ), 2-amino-3,8-dimethyl-imidazo[4,5-f]quinoxaline (MeIQx), 2-amino-1…
Sensitive Analysis of Retinyl Esters by Isocratic Adsorption Chromatography
1989
A sensitive method for the determination of retinyl esters, including their geometric isomers, by isocratic adsorption HPLC is described. The development of a special recycling system allows the separation of all-trans-, 13-cis, 11-cis- and 9-cis-retinyl palmitate, -stearate, -oleate, -palmitoleate and -linoleate with short retention times and high sensitivity. Extraction of the retinyl esters from various organs with mobile phase avoids additional evaporation steps. The method was evaluated by the determination of retinyl esters in small tissue samples such as tongue, trachea and inner ear. This is the first report of the detection of retinyl esters in these tissues, which are known to dep…
Contribution of vitamin A to the oxidation resistance of human low density lipoproteins.
1995
This study investigated the antioxidant contribution of vitamin A in protecting human low density lipoprotein (LDL) against copper-stimulated oxidation. The presence of small amounts of retinol (0.033 ± 0.012 nmol/mol LDL) and retinyl palmitate (0.036 ± 0.021 nmol/mol LDL) was routinely ascertained in the LDL. A single oral supplementation with 20,000 IU vitamin A caused a two- to three-fold increase of retinol and retinyl palmitate in the LDL isolated 8 h after the supplementation. In comparison to autologous-control LDL, vitamin A-enriched LDL were more resistant to oxidation, as expressed both by a clear delay in the onset of lipid peroxidation and by a reduction of the rate of conjugate…
Antioxidant Activity of Vitamin A within Lipid Environments
1998
New information about deleterious effects of free radicals on cell compartments, and a growing amount of associations between free radicals and various pathological conditions, have produced considerable interest in the biological defense systems against oxidative injury. The antioxidant properties of vitamin A, known for decades (Monaghan and Schmitt, 1932), have been reinvestigated in recent years in chemical as well as in biological systems. Its lipid nature and the localization within the lipophilic compartment of membranes and lipoproteins make vitamin A effective in reducing lipid peroxidation by acting as a chain-breaking antioxidant.
A time-course investigation of vitamin A levels and drug metabolizing enzyme activities in rats following a single treatment with prototypic polychlo…
1987
Xenobiotics previously characterized as selective inducers of drug-metabolizing enzymes were chosen to probe possible relationships between enzyme induction and vitamin A metabolism. Liver, kidney and serum retinol and retinyl palmitate levels were investigated in male Sprague--Dawley rats receiving a single i.p. injection of the polychlorinated biphenyls (PCBs), 2,2',5,5'-tetrachlorobiphenyl, 3,3',4,4'-tetrachlorobiphenyl or 2,2',4,4',5,5'-hexachlorobiphenyl (300 mumol/kg) or 1,1,1-trichloro-2,2-bis-(4-chlorophenyl)-ethane (DDT) (150 mumol/kg). While 2,2',5,5'-tetrachlorobiphenyl, a weak or non-inducer, and 2,2',4,4',5,5'-hexaclorobiphenyl and DDT, phenobarbital-type inducers of cytochrome…