Search results for "vitamin A"

Influence of vitamin A status on the regulation of uridine (5′-)diphosphate-glucuronosyltransferase (UGT) 1A1 and UGT1A6 expression by L-triiodothyro…

2001

The uridine (5′-)diphosphate-glucuronosyltransferases (UGT) are involved in the phase II of various xenobiotics and endogenous compounds. They are responsible for glucuronidation of many substrates, especially including bilirubin (UGT1A1) and phenolic compounds (UGT1A6). We previously showed that the expression of both isoforms is regulated at the transcriptional level by thyroid hormone in rat liver. In this present study, effects of vitamin A dietary intake (0, 1.72, 69 ug retinol acetate/g food) on the regulation of UGT1A1 and UGT1A6 activity and expression by 3,5,3′ triiodo-L-THYRONINE (l-T3) were examined in the same organ. Activities were determined toward bilirubin and 4-nitrophenol.…

Modulation of aflatoxin B1 carcinogenicity, genotoxicity and metabolism in rat liver by dietary carotenoids: evidence for a protective effect of CYP1…

1997

The effects of several carotenoids of vitamin A and of 3-methylcholanthrene have been tested on the initiation of hepatocarcinogenesis by aflatoxin B1, using the sequential protocol of Solt and Farber. AFB1-induced DNA single-strand breaks and AFB1-metabolism were also assessed. The P4501A inducer carotenoids (canthaxanthin, astaxanthin, beta-apo-8'-carotenal) and 3-methylcholanthrene reduce the carcinogenicity of AFB1, divert AFB1-metabolism into the less genotoxic aflatoxin M1 and reduce AFB1-induced DNA single-strand breaks: we conclude that these carotenoids exert their protective effect through the deviation of AFB1 metabolism towards detoxification pathways. beta-Carotene decreased AF…

Dietary carotenoids inhibit aflatoxin B1-induced liver preneoplastic foci and DNA damage in the rat: Role of the modulation of aflatoxin B1 metabolism

1998

To study the effects of carotenoids on the initiation of liver carcinogenesis by aflatoxin B1 (AFB1), male weanling rats were fed beta-carotene, beta-apo-8'-carotenal, canthaxanthin, astaxanthin or lycopene (300 mg/kg diet), or an excess of vitamin A (21000 RE/kg diet), or were injected i.p. with 3-methylcholanthrene (3-MC) (6 x 20 mg/kg body wt) before and during i.p. treatment with AFB1 (2 x 1 mg/kg body wt). The rats were later submitted to 2-acetylaminofluorene treatment and partial hepatectomy, and placental glutathione S-transferase-positive liver foci were detected and quantified. The in vivo effects of carotenoids or of 3-MC on AFB1-induced liver DNA damage were evaluated using diff…

Sensitive Analysis of Retinyl Esters by Isocratic Adsorption Chromatography

1989

A sensitive method for the determination of retinyl esters, including their geometric isomers, by isocratic adsorption HPLC is described. The development of a special recycling system allows the separation of all-trans-, 13-cis, 11-cis- and 9-cis-retinyl palmitate, -stearate, -oleate, -palmitoleate and -linoleate with short retention times and high sensitivity. Extraction of the retinyl esters from various organs with mobile phase avoids additional evaporation steps. The method was evaluated by the determination of retinyl esters in small tissue samples such as tongue, trachea and inner ear. This is the first report of the detection of retinyl esters in these tissues, which are known to dep…

Vitamin A and ciliated cells I. Respiratory epithelia

1986

To estimate the role of vitamin A on ciliated cells we investigated whether ciliated cells undergo any alteration during vitamin A deficiency. The epithelia examined include the ciliated cells of the respiratory tract and the ciliated sensory cells of the inner ear, the tongue, and the olfactory cells. This part of the paper will describe the ciliated epithelium of the tracheobronchial tract and its relation to vitamin A status. During vitamin A deficiency a partial loss of ciliae can be observed before any squamous metaplasia (which usually occurs during longer lasting vitamin A deficiency) develops. The scanning electron microscopic data illustrate the altered surface of the epithelium du…

?-Carotene Supplements Cannot Meet All Vitamin A Requirements of Vitamin A-Deficient Rats

1993

Crystalloid Lysozyme Inclusions in Paneth Cells of Vitamin A-Deficient Rats

1992

The effect of vitamin A-deficiency on jejunal Paneth cells in rats was investigated. Crystalloid particles were observed in secretion granules of Paneth cells from 6 out of 8 rats with vitamin A-deficiency. The particles were similar to those found in Paneth cells under other experimental conditions. Using an immuno-electron-microscopic technique we demonstrated a clear lysozyme immunoreactivity of these particles. In 2 vitamin A-deficient rats tubular structures have been detected in addition to the crystalloid particles. Crystalloid particles or tubular structures were not detectable in a control group of 8 vitamin A-supplemented rats. The morphological alterations of Paneth cells may be …

Vitamin A Deficiency Increases Protein Catabolism and Induces Urea Cycle Enzymes in Rats

2010

Chronic vitamin A deficiency induces a substantial delay in the rates of weight and height gain in both humans and experimental animals. This effect has been associated with an impaired nutrient metabolism and loss of body protein. Therefore, we analyzed the effect of vitamin A deficiency on endogenous proteolysis and nitrogen metabolism and its reversibility with all-trans retinoic acid (RA). Male weanling rats, housed in pairs, were pair-fed a vitamin A-deficient (VAD) or control diet until they were 60 d old. A group of deficient rats were further treated with daily intraperitoneal injections of all-trans RA for 10 d. Final body and tissue (i.e. liver and heart) weights were significantl…

Association between a SLC23A2 gene variation, plasma vitamin C levels, and risk of glaucoma in a Mediterranean population

2011

Purpose Several dietary factors have been associated with glaucoma. Among them, dietary antioxidant intake (i.e., vitamin C and vitamin A) in association with glaucoma has been analyzed, but with mixed results. Genetic factors may play a role in modulating the effect of dietary antioxidant intake on glaucoma; however, nutrigenetic studies in this field are scarce. Our aim was to study the association between selected polymorphisms in key proteins related to vitamin C and vitamin A concentrations and primary open-angle glaucoma (POAG). Methods We performed a case-control study matched for age, sex, and bodyweight. We recruited 300 subjects (150 POAG cases and 150 controls) from a Mediterrane…

Changes inα-tocopherol and retinol levels during cardiopulmonary bypass correlate with maximal arterial partial pressure of oxygen

2007

Cardiopulmonary bypass (CPB) is associated with oxidative stress. This study examined antioxidant levels in adults undergoing CPB surgery and their correlation with clinical variables. Arterial blood samples were obtained from 27 patients undergoing CPB. The time-course variation of vitamin C (spectrofluorimetry), alpha-tocopherol and retinol (HPLC) levels were determined. Plasma vitamin C rose initially but gradually decayed during reperfusion until 60% reduction of baseline values post-surgery. alpha-Tocopherol and retinol were reduced along CPB with post-operative values approximately 25% lower than baseline. No significant changes were found for selenium and glutathione peroxidase. PaO(…