A. Catharine Ross

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The acute inflammatory response to tissue injury and infection is associated with low concentrations of plasma retinol and its specific transport proteins, retinol-binding protein (RBP) and transthyretin (TTR). To examine the kinetics and mechanism of hyporetinemia, we have induced acute inflammation with lipopolysaccharide (LPS, from Pseudomonas(More)
Retinoic acid (RA), through nuclear retinoid receptors, regulates the expression of numerous genes. However, little is known of the biochemical mechanisms that regulate RA concentration in vivo. CYP26 (P450RAI), a novel cytochrome P450, is expressed during embryonic development, induced by all-trans RA, and capable of catalyzing the oxidation of [3H]RA to(More)
Previous studies have indicated the presence of both neutral and acid, bile salt-independent retinyl ester hydrolases associated with plasma membrane and endosome fractions of rat liver homogenates. In the present studies, chylomicrons containing tritium-labeled retinyl esters were injected intravenously into rats in order to study the initial metabolism of(More)
Apolipoprotein A-I (apoA-I) gene expression is known to be regulated by nutritional and hormonal factors. Experiments were conducted to determine the effects of vitamin A deficiency and retinoic acid repletion on the in vivo expression of apoA-I in rat intestine and liver. The relative abundance of apoA-I mRNA (apoA-I/beta-actin ratio) in the intestine did(More)
Vitamin A (VA, retinol) metabolism is homeostatically controlled, but little is known of its regulation in the postnatal period. Here, we determined the postnatal trajectory of VA storage and metabolism in major compartments of VA metabolism-plasma, liver, lung, and kidney from postnatal (P) day 1 to adulthood. We also investigated the response to(More)
Because vitamin A in milk is largely present as esterified retinol while blood plasma predominantly contains unesterified retinol, experiments were conducted to determine whether membranes from the lactating mammary gland are able to synthesize retinyl esters in vitro. When microsomes from rats lactating for 7 to 14 days were incubated with [(3)H]retinol(More)
The influence of extracellular fatty acids on the uptake and esterification of [3H]retinol bound to human retinol-binding protein (RBP), to RBP-transthyretin (TTR), or in dispersed form by the human hepatoma, HepG2, and human mammary epithelial carcinoma, MCF-7, cell lines was studied. The esterification of [3H]retinol was significantly increased in cells(More)
Microsomes from liver and several other tissues esterify retinol through both fatty acyl-CoA-dependent and -independent reactions. Two activities, acyl-CoA:retinol acyltransferase (ARAT) and lecithin:retinol acyltransferase (LRAT) activities, have been characterized enzymatically but neither has yet been purified and characterized biochemically. We have(More)
Little is known about the contribution of different tissues to whole-body vitamin A (VA) kinetics in neonates. Here, we have used model-based compartmental analysis of tissue tracer kinetic data from unsupplemented (control) and VA-retinoic acid (VARA)-supplemented neonatal rats to determine VA kinetics in specific tissues under control and supplemented(More)
Roles of all-trans-retinoic acid (tRA), a metabolite of vitamin A (VA), in both tolerogenic and immunogenic responses are documented. However, how tRA affects the development of systemic autoimmunity is poorly understood. Here we demonstrate that tRA have paradoxical effects on the development of autoimmune lupus in the MRL/lpr mouse model. We administered,(More)