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South African Medical Journal =... Jan 1993
Topics: Child; Humans; Measles; Vitamin A
PubMed: 8424212
DOI: No ID Found -
Xenobiotica; the Fate of Foreign... May 20171. The exposed level of vitamin A in plasma might be exceeded due to the both inadvertent and clinical utilization. The adverse effects of vitamin A have been frequently...
1. The exposed level of vitamin A in plasma might be exceeded due to the both inadvertent and clinical utilization. The adverse effects of vitamin A have been frequently reported, however, the mechanism remains unclear. The inhibition of vitamin A on the activity of UDP-glucuronosyltransferases (UGTs) was determined using in vitro incubation system to explain the adverse effects of vitamin A from a new perspective. 2. UGT supersomes catalyzed glucuronidation of 4-methylumbelliferone (4-MU), trifluoperazine (TFP), and cotinine was used as the probe reaction to evaluate the inhibition of vitamin A toward UGT isoforms, and 100 μM of vitamin A significantly inhibited the activity of all the tested UGT isoforms. Vitamin A exerted competitive inhibition on the activity of UGT1A1, 2B4, 2B7, and 2B15, and the inhibition kinetic parameters (K) were calculated to be 31.1, 16.8, 2.2, and 11.6 μM for UGT1A1, 2B4, 2B7, and 2B15. In silico docking method was used to try to elucidate the inhibition mechanism of vitamin A toward UGT2B7. The results showed the significant contribution of hydrogen bonds and hydrophobic interaction on the UGT2B7 inhibition by vitamin A. 3. The present study provides a new perspective for the adverse effects of vitamin A through reporting the inhibition of vitamin A on the activity of important phase II drug-metabolizing enzymes UGTs, which benefits our deep understanding of mechanism of vitamin A's adverse effects when high exposure of vitamin A occurs.
Topics: Enzyme Inhibitors; Glucuronosyltransferase; Hymecromone; Kinetics; Vitamin A
PubMed: 27359323
DOI: 10.1080/00498254.2016.1198841 -
American Journal of Physiology. Heart... Feb 2008
Topics: Animals; Cardiomegaly; Echocardiography; Humans; Signal Transduction; Vitamin A
PubMed: 18178713
DOI: 10.1152/ajpheart.00002.2008 -
The Western Journal of Medicine Jan 1990
Topics: Female; Humans; Pregnancy; Vitamin A
PubMed: 2309476
DOI: No ID Found -
The American Review of Respiratory... Nov 1989The hypothesis that vitamin A, or foods rich in vitamin A such as milk, protects against the development of airway obstruction was tested in a subsample of data from the...
The hypothesis that vitamin A, or foods rich in vitamin A such as milk, protects against the development of airway obstruction was tested in a subsample of data from the 1971-1975 National Health and Nutrition Examination Survey. The relative risk (estimated by relative odds) of having airway obstruction, defined as a FEV1/FVC less than or equal to 65%, was measured for different levels of nutrient and food group intakes after adjustment for age, sex, Quetelet Index, caloric intake, and cigarette smoking. Among the white respondents (never smokers or current smokers) whose recalled diet could be considered as typical of their usual diet, the relative odds of having airway obstruction was inversely related to vitamin A intake (x2 for trend = 7.2, p less than 0.01). In the analysis by food groups, the adjusted relative odds of airway obstruction for meat and poultry were 2.4 (95% confidence limits: 1.0 to 5.8) and for milk 1.6 (95% confidence limits: 1.0 to 2.5). The association of airway obstruction with lack of vitamin A or milk intake was clearer among smokers. These findings suggest that a diet poor in vitamin A increases the risk of airway obstruction, and are consistent with the previously reported association of chronic bronchitis, milk intake, and smoking.
Topics: Adult; Aged; Airway Obstruction; Diet; Female; Humans; Male; Middle Aged; Smoking; Statistics as Topic; Vitamin A
PubMed: 2817593
DOI: 10.1164/ajrccm/140.5.1312 -
The Journal of Infectious Diseases Mar 2006
Topics: Dietary Supplements; Humans; Immunity; Treatment Outcome; Vitamin A
PubMed: 16479507
DOI: 10.1086/500369 -
Jornal de Pediatria 2015To investigate the effect of vitamin A supplementation on the retinol concentration in colostrum under fasting and postprandial conditions.
OBJECTIVE
To investigate the effect of vitamin A supplementation on the retinol concentration in colostrum under fasting and postprandial conditions.
METHODS
This was a quasi-experimental study, with before and after assessments, conducted with 33 patients treated at a public maternity hospital. Blood and colostrum samples were collected under fasting conditions in the immediate postpartum period. A second colostrum collection occurred two hours after the first meal of the day, at which time a mega dose of 200,000 IU of retinyl palmitate was administered. On the following day, the colostrum was collected again under fasting and postprandial conditions. Serum and colostrum retinol concentrations were determined by high performance liquid chromatography.
RESULTS
The serum retinol concentration was 37.3 (16.8-62.2) μg/dL, indicating adequate nutritional status. The colostrum retinol concentration before supplementation was 46.8 (29.7-158.9) μg/dL in fasting and 67.3 (31.1-148.7) μg/dL in postprandial condition (p < 0.05), showing an increase of 43.8%. After supplementation, the values were 89.5 (32.9-264.2) μg/dL and 102.7 (37.3-378.3) μg/dL in fasting and postprandial conditions, respectively (p < 0.05), representing an increase of 14.7%.
CONCLUSIONS
This study demonstrated that maternal supplementation with high doses of vitamin A in postpartum resulted in a significant increase of the retinol concentration in colostrum under fasting conditions, with an even greater increase after a meal.
Topics: Adolescent; Adult; Chromatography, High Pressure Liquid; Colostrum; Dietary Supplements; Diterpenes; Fasting; Female; Humans; Non-Randomized Controlled Trials as Topic; Postpartum Period; Postprandial Period; Pregnancy; Retinyl Esters; Vitamin A; Young Adult
PubMed: 25193595
DOI: 10.1016/j.jped.2014.05.004 -
Nihon Rinsho. Japanese Journal of... Oct 1999Vitamin A research has been facing the third wave which was initiated both by a cloning of nuclear retinoid receptors and therapeutic application of retinoic acid for... (Review)
Review
Vitamin A research has been facing the third wave which was initiated both by a cloning of nuclear retinoid receptors and therapeutic application of retinoic acid for acute promyelocytic leukemia. The third wave also gives rise to confusion between vitamin A, retinoids, and retinoate analogues. Physiological functions of vitamin A still remain almost unresolved at a molecular level except a visual cycle. Future study may unravel a molecular involvement of vitamin A in sensation such as smelling, hearing and tasting, and a specific role of vitamin A in dopaminergic neuron will be presented in the near future. A refined control mechanism for intracellular level of retinoic acid is also discussed with retinal dehydrogenase II and cytochrome P450 RAI (CYP26).
Topics: Animals; Humans; Vitamin A
PubMed: 10540859
DOI: No ID Found -
The American Journal of Clinical... Sep 2000Wheat flour is a possible food vehicle for vitamin A fortification. (Clinical Trial)
Clinical Trial Randomized Controlled Trial
BACKGROUND
Wheat flour is a possible food vehicle for vitamin A fortification.
OBJECTIVE
This study assessed the efficacy of consumption of a vitamin A-fortified wheat-flour bun (pandesal) on the vitamin A status of school-age children.
DESIGN
This was a double-masked clinical trial conducted in 396 and 439 children aged 6-13 y attending 4 rural schools in the Philippines. The children were randomly assigned to a vitamin A-fortified (experimental) or nonfortified (control) group. A 60-g vitamin A-fortified pandesal (containing approximately 133 microg retinol equivalents) or a nonfortified pandesal was consumed by the children 5 d/wk for 30 wk. Vitamin A status, hemoglobin concentration, anthropometric status, morbidity, and dietary intake were assessed at baseline and 30 wk later. A modified relative dose response (MRDR) was assessed in a subsample of 20% of the children ( approximately 75/group) with the lowest initial serum retinol concentration at the 30-wk follow-up.
RESULTS
Baseline serum retinol significantly modified the effect of the intervention. The fortified group, whose initial serum retinol concentrations were below the median, had a 0.07 +/- 0.03-micromol/L greater improvement in serum retinol at the 30-wk follow-up than did the control group (P: = 0.02). Improved vitamin A status was also evident in the MRDR subsample. End-of-study differences in the MRDR showed that vitamin A- fortified pandesal intake decreased the percentage of children with inadequate liver vitamin A stores by 50% (15.3% compared with 28.6%; P: = 0.05).
CONCLUSIONS
Daily consumption of vitamin A-fortified pandesal significantly improved the vitamin A status of Filipino school-age children with marginal-to-low initial serum retinol concentrations.
Topics: Adolescent; Bread; Child; Double-Blind Method; Female; Flour; Food, Fortified; Humans; Liver; Male; Osmolar Concentration; Philippines; Schools; Triticum; Vitamin A
PubMed: 10966892
DOI: 10.1093/ajcn/72.3.738 -
Zeitschrift Fur Ernahrungswissenschaft Jun 1984Since the first characterization and description of vitamin A this is used in otolaryngologic therapy for different forms of hearing disorders, and its relation to the... (Review)
Review
Since the first characterization and description of vitamin A this is used in otolaryngologic therapy for different forms of hearing disorders, and its relation to the inner ear is subject of investigation. Animal experiments and clinical studies were done to clarify the significance of vitamin A for the function of hearing. Besides this there were a lot of observations describing correlations between vitamin A metabolism and hearing loss. Recent investigations showed that vitamin A is present in high concentrations in the inner ear and stored there. Morphological experiments revealed different and in some way contradictory results, but they showed that vitamin A seems to be essential for inner-ear morphogenesis.
Topics: Animals; Ear, Inner; Hearing Disorders; Humans; Vitamin A; Vitamin A Deficiency
PubMed: 6382839
DOI: 10.1007/BF02021685