The transfer of retinoic acid, retinyl acetate, and retinyl palmitate between single unilamellar vesicles was studied by resonance energy transfer. The retinoic acid transfers spontaneously between single unilamellar vesicles with a first order rate constant of 9.6 s-1 at 15 degrees C and pH 7.4. At 30 degrees C, the transfer rate was 3.5 times faster than that at 10 degrees C. At pH 7.4, the t...

Vitamin A (retinol) is a fat-soluble alcohol and is derived in the upper part of the small intestine from carotenoid plant pigments and Vitamin A esters present in food (Olson, I964). The free retinol then penetrates through the mucosal cells, perhaps aided by its polar or hydrophilic hydroxy group, and is re-esterified during transit (Glover and Walker, I 964). After absorption it reaches the ...

β -Lactoglobulin is capable of binding fat-soluble compounds including vitamin A palmitate and is suggested to specifically enhance intestinal uptake of retinol. In this study, bioavailability of a vitamin-A-retinyl palmitate complex in skim milk and in water-based liquids was investigated in vitamin-A-depleted rats. First, rats were fed a vitamin-A-free pellet diet for 6 wk and were thereafter...

Retinol and retinyl esters are measured in serum or plasma samples by gradient, normal-phase, adsorption "high-performance" liquid chromatography, with ultraviolet detection at 325 nm. The four major circulating retinyl esters in humans (esters of palmitate, stearate, oleate, and linoleate) are coeluted as a single peak. Retinyl acetate is included as an internal standard, to correct for variab...

The enzyme retinol saturase (RetSat) catalyzes the saturation of all-trans-retinol to produce (R)-all-trans-13,14-dihydroretinol. As a peroxisome proliferator-activated receptor (PPAR) gamma target, RetSat was shown to be required for adipocyte differentiation in the 3T3-L1 cell culture model. To understand the mechanism involved in this putative proadipogenic effect of RetSat, we studied the c...

There are two major dietary sources of vitamin A: easily absorbed retinyl palmitate in foods of animal origin, and poorly bioavailable carotenoids from plant foods. Plasma retinol is tightly controlled, probably by regulation of retinol-binding protein (RBP) formation in the liver, and only hormonal factors (e.g. oral contraceptives) and infection will alter the homeostasis. Delivery of retinol...

The relationship of dietary vitamin A transfer from mother to fetus is not well understood. The difference in swine offspring liver reserves was investigated between single-dose vitamin A provided to the mother post-conception compared with continuous provitamin A carotenoid dietary intake from biofortified (enhanced provitamin A) orange maize (OM) fed during gestation and lactation. Vitamin A-...

BACKGROUND Intramuscular injections of vitamin A decrease the risk of broncho-pulmonary dysplasia. Admixture of vitamin A with surfactant as a lipophilic vehicle might be a less invasive modality. AIM Test physical properties of surfactant + vitamin A. METHODS Miscibility and surface activity were tested in surfactant supplemented with retinyl-acetate, -palmitate, 13-cis-, or all-trans-reti...

BACKGROUND Vitamin A (VA; retinol) supplementation is recommended for children aged >6 mo in countries with high rates of malnutrition, but the distribution and retention of VA in body tissues have not been extensively explored. OBJECTIVE We sought to determine the distribution and retention of VA in tissues of neonatal rats raised under VA-marginal conditions. METHODS Sprague-Dawley neonat...

Vitamin A supplementation of lactating mothers and of infants at the time of diphtheria-pertussis-tetanus (DPT) and oral polio vaccine (OPV) immunizations have both been suggested as measures to prevent deficiency among infants. This multicenter randomized, double-blind, placebo-controlled trial was conducted in Ghana, India and Peru to determine the effect of maternal vitamin A supplementation...