Search results for "Retinol"
showing 10 items of 74 documents
Treatment with essential amino acids in patients on chronic hemodialysis: a double blind cross-over study.
1978
Patients on chronic hemodialysis may suffer from a latent protein deficiency, and therapy with essential amino acids has been recommended. In a double blind cross-over study, 13 hemodialysis patients received orally 15.7 g of essential amino acids daily over a 3-month period. Patients were on a liberal diet, containing 1 g of protein per kilogram of body weight per day. Hemodialysis was adequate. Therapy resulted in an increase in urea, uric acid, C3 c complement factor and a fall in C4. Lysine levels increased and phenylalanine fell. Malnutrition could not account for the observed metabolic changes, which are more likely due to uremic metabolic disturbances. A liberal diet of 1 g of protei…
Levels of serum retinol-binding protein 4 before and after non-surgical periodontal treatment in lean and obese subjects: An interventional study
2018
AimWe aimed to evaluate serum RBP4 levels before and after periodontal therapy in lean and obese subjects with chronic periodontitis (CP) in order to determine its possible association with periodontitis. Materials and MethodsThis is an interventional study for which a total of 112 lean and 119 obese subjects were recruited. Patients with CP were evaluated before and after three months of non-surgical periodontal treatment. Periodontal, anthropometric, biochemical parameters and serum levels of TNF-, IL-6, hs-CRP and RBP4 were assessed. ResultsSerum RBP4 levels were associated with an increased probability of periodontitis (OR=1.60; 95% CI: 1.02-2.50), showing patients with CP to have highe…
Development and validation of a fast and sensitive chromatographic assay for all-trans-retinol and tocopherols in human serum and plasma using liquid…
2002
A sensitive HPLC assay for all-trans-retinol, alpha-tocopherol, and gamma-tocopherols in human serum and plasma is reported. Sample preparation is performed in one step and involves precipitation of proteins and extraction of lipids with two volumes of an ethanol-chloroform mixture (3:1, v/v) without I.S. addition. After removal of the precipitated protein, 20 microl aliquots of the supernatant (equivalent to 6.7 microl of serum or plasma) were injected into the HPLC system and analyzed using fluorometric detection. RP-HPLC was performed using a C(18) S3 ODS2 column with a methanol-water step gradient (97:3 to 100) at 1.0 ml/min. The quantification limit expressed as nanograms of analyte pe…
Antioxidant Activity of All-trans-retinol in Homogeneous Solution and in Phosphatidylcholine Liposomes
1993
A kinetic quantification of the lipoperoxyl radical-scavenging activity of all-trans-retinol has been carried out in homogeneous solution, when radicals were produced from the oxidation of methyl linoleate in methanol, initiated by the lipid-soluble 2,2′-azobis (2,4-dimethyl-valeronitrile) (AMVN) as well as in a soybean phosphatidylcholine membrane model, in which peroxidation was induced either by AMVN or the hydrophylic 2,2′-azobis(2-amidinopropane)hydrochloride (AAPH). The physical microenvironment contributes to the determination of antioxidant efficiency of all-trans-retinol. In homogeneous solution the kinetic constant kinh is 3.5 × 105 M-1 s-1 and appears of the same order of magnitu…
Antioxidant reactions of all-trans retinol in phospholipid bilayers: effect of oxygen partial pressure, radical fluxes, and retinol concentration.
1997
Lipoperoxyl radical-scavenging activity of retinol in unilamellar soybean phosphatidylcholine liposomes was studied under a variety of conditions to appreciate to what extend retinol may be considered an effective antioxidant. Peroxidation, initiated by 2 mM 2,2'-azobis(amidino-propane)hydrochloride (AAPH), was carried out at 160 torr O2 or at 15 torr O2, in the absence or in the presence of 10 to 40 mM retinol. As evaluated by the length of the inhibition periods, t(inh), and by the ratio between the inhibition and propagation rate, R(inh)/R(p), the antioxidant activity of retinol was higher at 15 torr O2 than at 160 torr O2. The consumption rate of retinol was markedly faster at 160 torr …
Retinyl ester hydrolases in retinal pigment epithelium.
1991
In bovine retinal pigment epithelium membranes we have found three hydrolases which were active against trans-retinyl palmitate. This was possible by assaying different subcellular fractions as a function of pH in the range 3-9. Detection of these activities has been favored by the use in the enzyme assay of Triton X-100, which has an activating effect up to a concentration of 0.03% at a detergent-protein ratio of about 1.5-3.0. Apparent kinetic parameters for the retinyl ester hydrolases have been determined after a study of the optimization of assay conditions. Vmax values for hydrolases acting at pH 4.5, 6.0, and 7.0 were, respectively, 156, 55, and 70 nmol/h/mg. To identify the subcellu…
Short Sleep Duration Is Related to Emerging Cardiovascular Risk Factors in Obese Children
2015
Objective: The aim of the present study was to evaluate the influence of sleep duration on cardiovascular risk factors in obese children. Methods: Cross-sectional analysis of 90 obese children ages 7 to 16 years. Anthropometric and clinical evaluation with specification of dietary and lifestyle habits was carried out during an office visit. Sleep duration was evaluated by the BEARS (B = bedtime issues, E = excessive daytime sleepiness, A = night awakening, R = regularity and duration of sleep, S = snoring) questionnaire on children's sleep characteristics. Sleep time adequacy by age was assessed according to the criteria of the National Sleep Foundation. Biochemical blood variables indicati…
Estradiol decreases xanthine dehydrogenase enzyme activity and protein expression innon-tumorigenicand malignant human mammary epithelial cells
2009
The retinoic acid deficiency in breast tumour epithelial cells has been ascribed to an insufficient expression of either the enzyme(s) involved in its biosynthesis or the cellular retinol binding protein (CRBP) or both. In an attempt to define the mechanisms underpinning retinoic acid deficiency in these cell model systems, we have investigated the potential regulatory effect of oestrogen (17β-estradiol) on one key player in retinoic acid biosynthesis, the xanthine dehydrogenase (XDH). This enzyme is consistently expressed and very active in non-malignant human mammary epithelial cells (HMEC), as opposed to tumour MDA-MB231 and MCF7 cells. In these latter two cell lines, as opposed to HMEC …
Retinol encapsulated into amorphous Ca2+ polyphosphate nanospheres acts synergistically in MC3T3-E1 cells
2015
Both the quality and quantity of collagen, the major structural component of the skin, decrease in aging skin. We succeeded to encapsulate retinol into amorphous inorganic polyphosphate (polyP) nanoparticles together with calcium ions ("aCa-polyP-NP"), under formation of amorphous Ca-polyP/retinol nanospheres ("retinol/aCa-polyP-NS"). The globular nanospheres are not cytotoxic, show an almost uniform size of ≈ 45 nm and have a retinol content of around 25%. Both components of those nanospheres, retinol and the aCa-polyP-NP, if administered together, caused a strong increase in proliferation of mouse calvaria MC3T3 cells. The expressions of collagen types I, II and III genes, but not the exp…
Tierexperimentelle Untersuchungen zur Abh�ngigkeit der Ototoxicit�t von der Dosierung des Kanamycin und zur Schutzwirkung durch Vitamine
1963
Mit einer einfachen Methodik wird die durch Kanamycin bei Ratten ausgeloste Horschadigung quantitativ gemessen. Die Abhangigkeit der Schwere der Horschadigung von der Dosis und vom Dosierungsschema wird bestimmt. Der Nachweis, das die Vitamine A oder D eine protektive Wirkung gegenuber der Ototoxicitat des Kanamycin besitzen, kann nicht erbracht werden. Die Folgerungen aus diesen toxikologischen Untersuchungen fur die Anwendung von Kanamycin am Menschen werden kurz erortert.