Retinyl esters are hydrolyzed in liver both during uptake and mobilization of vitamin A. Studies were conducted to explore the enzymatic hydrolysis of retinyl palmitate in normal rat liver. Retinyl palmitate hydrolase activity was assayed with a sensitive and accurate microassay, employing retinyl [~-‘~C]palmitate as substrate. The products of the reaction were identified as retinol and free fa...

Chronic obstructive pulmonary disease (COPD) is characterized by chronic airway inflammation. Cigarette smoke has been considered a major player in the pathogenesis of COPD. The inflamed airways of COPD patients contain several inflammatory cells. Vitamin A metabolites have been implicated in the repair of lung damage. Exposure to cigarette smoke has been shown to depress levels of retinol in l...

Serum vitamin A homeostasis was studied in rats with nonfiltering kidneys prepared by ligation of renal arteries. Within 1-2 h of acute renal failure, the serum retinol level increased by 11-73% and was maintained for at least 4 h. More than 90% of the increase in serum retinol was associated with retinol in the retinol binding protein-transthyretin (RBP-TTR) complex. The activities of acyl-CoA...

A method utilizing small disposable C18 bonded-phase columns has been developed to separate retinol and retinyl palmitate mixtures into their individual components in high yield and purity. Up to ten mixtures can be processed in 1 hr and the columns are reusable after suitable washing. Although the method was developed with standard retinoid mixtures, it was shown that it is also applicable to ...

Apo-retinal-binding protein (apo-RBP) from human plasma was found to bind all-trans-3-dehydroretinol and to protect the chromophore from degradation. The all-trans-3dehydroretinol-RBP complex, in turn, binds tightly to prealbumin at physiological ionic strength as judged by gel filtration chromatography. All trans 3 dehydroretinal also formed a complex with RBP but this complex did not bind to ...

The vitamin A (VA) value of carotenoids from fruits and vegetables is affected by many factors. This study determined the VA value of -carotene isolated from carrots compared with -carotene and retinyl acetate supplements fed to Mongolian gerbils (Meriones unguiculatus). Gerbils (n 38) were fed a VA-free diet for 4 wk. At baseline, 6 gerbils were killed to determine liver VA. Gerbils were divid...

Hereditary ichthyosis is a group of generalized hereditary keratinization disorders characterized by general dryness the skin, peeling, hyperkeratosis and often erythroderma. These manifestations are caused mutations in genes mainly involved formation skin barrier. divided into syndromic non-syndromic. Nonsyndromic ichthyoses include: vulgar ichthyosis, recessive X-linked autosomal congenital k...

We propose a single-run liquid-chromatographic determination, with ultraviolet detection at 330 nm, for serum retinol and retinyl esters. The vitamin A derivatives are extracted according to the Bligh-Dyer procedure. With 200 microliter or serum, the lower detection limit is 50 microgram/liter for retinol and about 100 microgram/liter for retinyl esters. Within-run precision (CV) was 2.3% for r...

We studied the effects of vitamin A deficiency and repletion on rat insulin release and islet cellular retinol binding protein (CRBP) and cellular retinoic acid binding protein (CRABP). Biphasic insulin release from vitamin A-deficient perifused islets was markedly impaired. Release remained impaired with retinoic acid (RA) repletion, 2 micrograms/g diet compared to release from islets of rats ...

Perfusion feeding in rats induced a decrease in circulating retinol despite an adequate supply of vitamin A. We studied the effect of total parenteral nutrition (TPN) on the retinol specific carrier in rat, analyzing holo-RBP (bound to retinol) and apo-RBP (without retinol) in serum and in liver. Vitamin A-sufficient (A+) and -deficient (A-) rats were characterized in terms of vitamin A and RBP...