A quantitative determination of physiological levels of all-trans-retinoic acid (vitamin A acid) in human serum has been developed. A double-phase extraction of 3.5 ml of serum followed by a specific and sensitive high performance liquid chromatography procedure allowed measurement of levels down to 1 ng/ml. Serum concentrations in 37 fasting volunteers ranged from 2.7 to 4.2 ng/ml and fitted a...

Retinoids, vitamin A (retinol) and its metabolic derivatives, are required for normal vertebrate development. In murine embryonic stem (ES) cells, which remain undifferentiated when cultured in the presence of LIF (leukemia inhibitory factor), little metabolism of exogenously added retinol takes place. After LIF removal, ES cells metabolize exogenously added retinol to 4-hydroxyretinol and 4-ox...

We purified retinol dehydrogenase from bovine rod outer segments using polyethylene glycol precipitation and hydroxylapatite, concanavalin A-Sepharose CL-4B, and Sepharose CL-6B column chromatography in the presence of NADP. We obtained 13-fold purification of retinol dehydrogenase with specific activity of 61.8 nmol/min/mg and 3.8% recovery. Sodium dodecyl sulfate-polyacrylamide gel electropho...

Cellular retinol-binding proteins (CRBPs) I and II, which are members of the intracellular lipid-binding protein (iLBP) family, are retinoid chaperones that are responsible for the intracellular transport and delivery of both retinol and retinal. Although structures of retinol-bound CRBPI and CRBPII are known, no structure of a retinal-bound CRBP has been reported. In addition, the retinol-boun...

Retinol, an established topical ingredient for improving signs of photo-aging, is often limited in concentration due to the potential low-level visible and sensory irritation. A new anhydrous, 0.5% stabilized retinol serum was developed, balancing bioactivity tolerability. This patented formula uses Relative Polarity Index (RPI) between skin, retinol, emollient ratios, allowing controlled bio-d...

A linear, first-order, constant-coefficient multicompartmental model is presented which describes the dynamics of [3H]retinol turnover in adult rats with normal plasma retinol concentrations but low liver stores (less than 100 micrograms of retinol equivalents). To fit plasma and tissue (liver, kidney, and rest of carcass) tracer and tracee data, eight physiological compartments were required i...

Vitamin A (retinol) is essential for normal mammalian development. However, its biological activity depends upon its conversion to retinoic acid (RA), a local mediator of cellular proliferation and differentiation. Previous studies have shown that embryonic RA is found specifically in tissues known to depend upon vitamin A for normal development and that its production follows uptake of materna...

Murine thymic T cells depleted of antigen-presenting cells proliferate poorly in response to crosslinking anti-CD3 monoclonal antibodies or concanavalin A when cultured in conventional fetal calf serum-containing serum. However, in a serum-free medium formulated to contain, in addition to basic ingredients, insulin, transferrin, albumin, linoleic acid (ITLB), and retinol, proliferation is vigor...