نتایج جستجو برای: retinol palmitate
تعداد نتایج: 9619 فیلتر نتایج به سال:
To explore the nature of retinyl ester synthesis by liver microsomes, membranes prepared from rat or cat liver were incubated under various conditions with [3H] retinol dispersed in dimethyl sulfoxide. When [3H]retinol, buffer, and microsomes were incubated together (basal conditions), some [3H]retinol esterification was consistently observed. However, the rate of esterification could be increa...
The key biochemical process of the vertebrate visual cycle required for rhodopsin regeneration, 11-cis-retinoid production from all-trans-retinoids, is shown to occur in vitro. A 600 X g supernatant from a frog retina/pigment epithelium homogenate transforms added all-trans-[3H]retinol, in a time-dependent fashion, to a mixture of 11-cis-retinol, 11-cis-retinal, and 11-cis-retinyl palmitate. 13...
Hydrolysis of retinyl esters by non-specific carboxylesterases from rat liver endoplasmic reticulum.
The four most important non-specific carboxylesterases from rat liver were assayed for their ability to hydrolyse retinyl esters. Only the esterases with pI 6.2 and 6.4 (= esterase ES-4) are able to hydrolyse retinyl palmitate. Their specific activities strongly depend on the emulsifier used (maximum rate: 440 nmol of retinol liberated/h per mg of esterase). Beside retinyl palmitate, these este...
OBJECTIVE To assess the effect of maternal supplementation with a single dose of retinyl palmitate during the postpartum period, in order to provide vitamin A for the infant. METHODS A clinical trial was conducted in Natal (Northern Brazil), between March and December 2007, on 85 women distributed randomly into two groups. The postpartum supplements of retinyl palmitate consisted of a single ...
Dietary vitamin A as retinyl ester is hydrolysed and re-esterified with long-chain fatty acids in the small intestine. The esterified vitamin A is subsequently stored in the liver, where it is hydrolysed to free retinol to be transported by carrier proteins to the target tissue. A decreased availability of retinol carrier proteins has been suggested to be responsible for affecting metabolic ava...
BACKGROUND It is not known whether daily consumption of vitamin A-containing foods is efficacious for treating nightblindness. OBJECTIVE We assessed the effect of supplementation with vitamin A from food or synthetic sources on dark adaptation and plasma retinol concentrations in nightblind pregnant Nepali women. DESIGN Nightblind pregnant women were randomly assigned to 1 of 6 treatment gr...
Retinoids are micronutrients that are stored as retinyl esters in the retina and hepatic stellate cells (HSCs). HSCs are key players in fibrogenesis in chronic liver diseases. The enzyme responsible for hydrolysis and release of retinyl esters from HSCs is unknown and the relationship between retinoid metabolism and liver disease remains unclear. We hypothesize that the patatin-like phospholipa...
The retinal epithelium plays an important role in the storage and metabolism of retinoids in the eye. Studies were conducted to examine the enzymatic hydrolysis of retinyl esters by human retinal epithelial cells. Homogenates prepared from these cells were found to hydrolyze both the 11-cis- and all-trans-isomers of retinyl palmitate. Retinyl ester hydrolysis was time-, protein-, and pH-depende...
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