scholarly journals Vitamin A economy of the developing chick embryo and of the freshly hatched chick

1973 ◽  
Vol 136 (3) ◽  
pp. 757-761 ◽  
Author(s):  
P. S. Joshi ◽  
S. N. Mathur ◽  
S. K. Murthy ◽  
J. Ganguly
Keyword(s):  
Chick Embryo ◽  
Vitamin A ◽  
Embryonic Tissue ◽  
Retinyl Esters ◽  
High Concentrations

1. The changes in the net amounts of retinol, retinyl esters and retinal in both the developing chick embryo and the newly hatched chick were investigated. The embryo requires about 68nmol of the vitamin for its growth, whereas the baby chick requires about 108nmol during the first 7 days after hatching. 2. Retinal was present in the egg in fairly high concentrations at the beginning of the incubation but it virtually disappeared from the extra-embryonic tissue after day 17 of incubation. It was not found in the liver of the embryo or of the newly hatched chick up until day 7.

The Effects of Vitamin A and Citral on Epithelial Differentiation in vitro 2. The Chick Oesophageal and Corneal Epithelia and Epidermis

Development ◽  
1963 ◽  
Vol 11 (3) ◽  
pp. 621-635
Author(s):  
Margaret B. Aydelotte
Keyword(s):  
Chick Embryo ◽  
Vitamin A ◽  
Culture Medium ◽  
Combined Effect ◽  
Tracheal Epithelium ◽  
Mucous Cells ◽  
Ciliated Cells ◽  
Low Concentrations ◽  
High Concentrations

The effects of vitamin A and citral on the differentiation of chick tracheal epithelium in vitro were described in a previous paper (Aydelotte, 1963a). High concentrations of vitamin A inhibited the development of tracheal mucous cells but the epithelium became well ciliated. Citral in low concentrations favoured the differentiation of mucous cells but few ciliated cells developed; in higher concentrations of citral the tracheal epithelium became stratified and occasionally keratinized. The changes produced by citral resembled those in the tracheal epithelium of vitamin A deficient chicks (Aydelotte, 1963b) and when vitamin A and citral were both added to the culture medium, the combined effect was intermediate between those given by the two compounds separately. These results, therefore, supported the suggestion put forward by Leach & Lloyd (1956) that citral inhibits vitamin A. The investigation of the effects of vitamin A and citral in vitro has been extended to the oesophageal and corneal epithelia and epidermis of the chick embryo.

scholarly journals South African preschool children habitually consuming sheep liver and exposed to vitamin A supplementation and fortification have hypervitaminotic A liver stores: a cohort study

2019 ◽  
Vol 110 (1) ◽  
pp. 91-101 ◽  
Author(s):  
Martha E van Stuijvenberg ◽  
Muhammad A Dhansay ◽  
Jana Nel ◽  
Devika Suri ◽  
Michael Grahn ◽  
...  
Keyword(s):  
South Africa ◽  
Preschool Children ◽  
Vitamin A ◽  
Total Serum ◽  
High Dose ◽  
Serum Retinol ◽  
Hypervitaminosis A ◽  
Total Liver ◽  
Before And After ◽  
Retinyl Esters

ABSTRACT Background In some regions, multiple vitamin A (VA) interventions occur in the same target groups, which may lead to excessive stores. Retinol isotope dilution (RID) is a more sensitive technique than serum retinol to measure VA status. Objective We evaluated VA status before and after a high-dose supplement in preschool children living in a region in South Africa with habitual liver consumption and exposed to VA supplementation and fortification. Methods After baseline blood samples, subjects (46.7 ± 8.4 mo; n = 94) were administered 1.0 μmol [14,15]-13C2-retinyl acetate to estimate total liver retinol reserves by RID with a follow-up 14-d blood sample. Liver intake was assessed with a frequency questionnaire. In line with current practice, a routine 200,000 IU VA capsule was administered after the RID test. RID was repeated 1 mo later. Serum retinyl esters were evaluated using ultra-performance liquid chromatography. Results At baseline, 63.6% of these children had hypervitaminosis A defined as total liver retinol reserves ≥1.0 μmol/g liver, which increased to 71.6% after supplementation (1.13 ± 0.43 to 1.29 ± 0.46 μmol/g; P < 0.001). Total serum VA as retinyl esters was elevated in 4.8% and 6.1% of children before and after supplementation. The odds of having hypervitaminosis A at baseline were higher in children consuming liver ≥1/mo (ratio 3.70 [95% CI: 1.08, 12.6]) and in children receiving 2 (4.28 [1.03, 17.9]) or 3 (6.45 [0.64, 65.41]) supplements in the past 12 mo. Total body stores decreased after the supplement in children in the highest quartile at baseline compared with children with lower stores, who showed an increase (P = 0.007). Conclusions In children, such as this cohort in South Africa, with adequate VA intake through diet, and overlapping VA fortification and supplementation, preschool VA capsule distribution should be re-evaluated. This trial was registered at https://clinicaltrials.gov/ct2/show/NCT02915731 as NCT02915731.

FURTHER STUDIES ON THE DUAL REQUIREMENT FOR PHENYLALANINE AND TYROSINE IN TISSUE CULTURE

1961 ◽  
Vol 39 (5) ◽  
pp. 925-932 ◽  
Author(s):  
Helen J. Morton ◽  
Joseph F. Morgan
Keyword(s):  
Amino Acids ◽  
Tissue Culture ◽  
Chick Embryo ◽  
Heart Cells ◽  
Present System ◽  
Chick Heart ◽  
High Concentrations ◽  
Chick Embryo Heart ◽  
Embryo Heart ◽  
Related Compounds

Seventeen structurally related compounds were tested for their ability to substitute for phenylalanine or tyrosine in the nutrition of chick embryo heart fragments. DL-Alanyl-DL-phenylalanine replaced phenylalanine. All other compounds had negligible effects, and most were toxic at high concentrations. β-Phenylserine, a phenylalanine antagonist, actually prolonged the survival of chick heart cells but only if both phenylalanine and tyrosine were present. Similarly, optimal reversal of β-phenylserine toxicity was dependent on the presence of both amino acids. Although phenylalanine and tyrosine are not interconvertible in the present system, it has been shown that three phenylalanine antagonists, p-fluorophenylalanine, β-2-thienylalanine, and β-phenylserine, can be identified by their relationship to tyrosine, rather than to phenylalanine.

scholarly journals Vitamin A Transporters in Visual Function: A Mini Review on Membrane Receptors for Dietary Vitamin A Uptake, Storage, and Transport to the Eye

Nutrients ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 3987
Author(s):  
Nicasio Martin Ask ◽  
Matthias Leung ◽  
Rakesh Radhakrishnan ◽  
Glenn P. Lobo
Keyword(s):  
Cell Growth ◽  
Vitamin A ◽  
Visual Function ◽  
Binding Protein ◽  
Retinol Binding Protein ◽  
Dietary Vitamin ◽  
Peripheral Tissues ◽  
Retinol Binding Protein 4 ◽  
Retinyl Esters ◽  
And Function

Vitamins are essential compounds obtained through diet that are necessary for normal development and function in an organism. One of the most important vitamins for human physiology is vitamin A, a group of retinoid compounds and carotenoids, which generally function as a mediator for cell growth, differentiation, immunity, and embryonic development, as well as serving as a key component in the phototransduction cycle in the vertebrate retina. For humans, vitamin A is obtained through the diet, where provitamin A carotenoids such as β-carotene from plants or preformed vitamin A such as retinyl esters from animal sources are absorbed into the body via the small intestine and converted into all-trans retinol within the intestinal enterocytes. Specifically, once absorbed, carotenoids are cleaved by carotenoid cleavage oxygenases (CCOs), such as Beta-carotene 15,15’-monooxygenase (BCO1), to produce all-trans retinal that subsequently gets converted into all-trans retinol. CRBP2 bound retinol is then converted into retinyl esters (REs) by the enzyme lecithin retinol acyltransferase (LRAT) in the endoplasmic reticulum, which is then packaged into chylomicrons and sent into the bloodstream for storage in hepatic stellate cells in the liver or for functional use in peripheral tissues such as the retina. All-trans retinol also travels through the bloodstream bound to retinol binding protein 4 (RBP4), where it enters cells with the assistance of the transmembrane transporters, stimulated by retinoic acid 6 (STRA6) in peripheral tissues or retinol binding protein 4 receptor 2 (RBPR2) in systemic tissues (e.g., in the retina and the liver, respectively). Much is known about the intake, metabolism, storage, and function of vitamin A compounds, especially with regard to its impact on eye development and visual function in the retinoid cycle. However, there is much to learn about the role of vitamin A as a transcription factor in development and cell growth, as well as how peripheral cells signal hepatocytes to secrete all-trans retinol into the blood for peripheral cell use. This article aims to review literature regarding the major known pathways of vitamin A intake from dietary sources into hepatocytes, vitamin A excretion by hepatocytes, as well as vitamin A usage within the retinoid cycle in the RPE and retina to provide insight on future directions of novel membrane transporters for vitamin A in retinal cell physiology and visual function.

Serum vitamin A, retinyl esters and vitamin E in nephrotic syndrome

1991 ◽  
Vol 23 (4) ◽  
pp. 399-405 ◽  
Author(s):  
M. Mydlík ◽  
K. Derzsiová ◽  
M. Brátová ◽  
Š. Havriš
Keyword(s):  
Nephrotic Syndrome ◽  
Vitamin E ◽  
Vitamin A ◽  
Serum Vitamin ◽  
Retinyl Esters

THE USE AND ABUSE OF VITAMIN A

PEDIATRICS ◽  
1971 ◽  
Vol 48 (4) ◽  
pp. 655-656
Author(s):  
Sumner J. Yaffe ◽  
L. J. Filer
Keyword(s):  
Vitamin A ◽  
High Potency ◽  
Over The Counter ◽  
High Concentrations

The grave risks resulting from the unrestricted sale of high concentrations of vitamin A make it imperative that an active curb, by appropriate legislation if necessary, be placed on the over-the-counter marketing of high potency vitamin A preparations. Physicians should be aware of the vitamin A content in the preparations they prescribe for their patients. They also should caution parents regarding the dangers of overdosage of this vitamin.

Simultaneous determination of retinol and retinyl esters in serum or plasma by reversed-phase high-performance liquid chromatography.

1978 ◽  
Vol 24 (11) ◽  
pp. 1920-1923 ◽  
Author(s):  
M G DeRuyter ◽  
A P De Leenheer
Keyword(s):  
Vitamin A ◽  
High Performance ◽  
Chromatographic Determination ◽  
Reversed Phase ◽  
Retinyl Palmitate ◽  
Serum Retinol ◽  
Liquid Chromatographic Determination ◽  
Retinyl Esters ◽  
Liquid Chromatographic

Abstract 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 retinol, 4.3% for retinyl palmitate. Day-to-day percision (CV, n = 20) for retinol was 4.9% during a month. The method can be used for the assessment of vitamin A absorption tests and for the determination of serum retinol (normal, subnormal, and above-normal concentrations). Serum retinyl esters can only be measured in conditions where concentrations exceed 100 microgram/liter.

The influence of β-carotene supplementation on β-carotene concentration in the corpus luteum and on hormone concentration in the plasma of heifers

2001 ◽  
Vol 26 (2) ◽  
pp. 359-362
Author(s):  
G. Flachowsky ◽  
M. Schlenzig ◽  
Brigitta Kirsche ◽  
P. Lebzien
Keyword(s):  
Body Weight ◽  
Vitamin A ◽  
Corpus Luteum ◽  
Hormone Concentration ◽  
High Vitamin ◽  
High Concentrations ◽  
Different Levels ◽  
Β Carotene ◽  
Average Body ◽  
Average Body Weight

AbstractThe objective of the study was to investigate the influence of different levels of β-carotene supplements on the β-carotene concentration in the corpus luteum and on hormone concentrations in the plasma of heifers. 32 heifers (average body weight: 371 kg) were fed a low carotene diet (< 1 mg per kg DM) for 120 days. The heifers were divided into four groups according to body weight and age and supplied with 0, 100, 200 or 300 mg β-carotene per animal and day. Heifers were artifically inseminated after day 60 of the experiment and were slaughtered after day 120 of the experiment. Carotene concentration in the corpus luteum (2.3, 27, 50 and 81 μg/g for 0, 100, 200 and 300 mg β-carotene per animal per day), in plasma and in ovary was significantly influenced with increased carotene supplements. LH-concentration of plasma decreased and β-oestradiol-concentration increased with carotene supplementation. High concentrations of β-carotene in the corpus luteum and ovaries of cattle seem to act as a depot which is available when high vitamin A requirements during ovulation have to be met.

scholarly journals Serum retinyl esters are not elevated in postmenopausal women with and without osteoporosis whose preformed vitamin A intakes are high

2006 ◽  
Vol 84 (6) ◽  
pp. 1350-1356 ◽  
Author(s):  
Kristina L Penniston ◽  
Ning Weng ◽  
Neil Binkley ◽  
Sherry A Tanumihardjo
Keyword(s):  
Vitamin A ◽  
Postmenopausal Women ◽  
Retinyl Esters
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