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...

Background: Micronutrients deficiency is one of the most health problems in the world. Iron and zinc deficiency and their interaction with vitamin A are important, too. The aim of this study was to investigate the effects of supplementation of iron and zinc, alone or combined, on vitamin A status of primary school children. Material and methods: The study was a randomized double-blind clinica...

When EBV-transformed human B cells are removed from conventional cell cultures, washed, and seeded at a low cell density in serum-free medium, their growth potential is greatly diminished. Fresh serum restores the growth of low density B cell cultures. We have traced this restorative effect to an essential factor present in the lipid fraction of serum and have identified it as all-trans retinol...

To understand the signaling and growth-inhibitory effects of retinoids, we have examined the metabolism of [3H]retinol in a number of estrogen receptor-positive (ER+) and estrogen receptor-negative (ER-) human breast cancer cell lines. We have also assayed the metabolism of [3H]retinol in normal human mammary epithelial cells. The ER+ breast cancer cell lines MCF-7 and T47D produce [3H]4-oxoret...

Bovine and human retinol-retinol-binding protein (RBP) were iodinated to high specific activity. At least 34% of the iodinated material was native and retained its retinol chromophore as judged by its characteristic ability to bind to plasma prealbumin. Bovine and human retinol-125I-RBP were found to bind specifically to intact isolated pigment epithelium cells from bovine eyes. The specific bi...

Vitamin A (retinol) is absorbed in the small intestine, stored in liver, and secreted into circulation bound to serum retinol-binding protein (RBP4). Circulating retinol may be taken up by extrahepatic tissues or recycled back to liver multiple times before it is finally metabolized or degraded. Liver exhibits high affinity binding sites for RBP4, but specific receptors have not been identified...

The influence of an excess of retinol on bone formation was studied by using cultures of embryonic-chick calvaria. Retinol decreased collagen synthesis in a dose-dependent manner, non-collagenous protein synthesis being relatively unaffected. Collagen synthesis was significantly inhibited after 24 h of culture with retinol and was progressively decreased, compared with control cultures containi...

Postpartum vitamin A supplementation of mothers and infants is recommended, but the efficacy has been questioned. In this double-blind, placebo-controlled trial, Kenyan mother-infant pairs were randomised to maternal vitamin A (400,000 IU) or placebo <24 h postpartum, and infant vitamin A (100,000 IU) or placebo at 14 weeks. Milk retinol was determined at weeks 4, 14 and 26, and maternal and in...

1. The effects of retinol and retinoic acid supplementation of retinol-deficient rats were studied for a variety of metabolic processes shown to be affected by retinol-deficiency. 2. Retinol-deficient rats were found to have decreased body-weight, liver and testes weights, a degeneration of testicular germinal cells, an increased incorporation of labelled choline into liver and testes phospholi...

Fenretinide (HPR) is a synthetic retinoid which has been shown to cause a reduction in the incidence of carcinogen-induced epithelial tumors in experimental animals, and it has been chosen to be tested as a chemopreventive agent in humans. A study on plasma concentrations of HPR, of its metabolite N-(4-methoxyphenyl)retinamide (MPR), and on its effects on endogenous retinol was performed in gro...