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Results 451 - 500 of 2378
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Ramos Luiz Antônio - - 2005
The preparation and electrochemical characterization of a carbon paste electrode modified with bis(N,N-piperidinedithiocarbamate)-mu-tris(N,N-piperidinedithiocarbamate)diruthenium(III) complex, alpha-[Ru2(Pip)5]Cl are described. The best voltammetric response was obtained for a 10% (m/m) alpha-[Ru2(Pip)5]Cl content in the paste, potassium acid phthalate solution pH 4.0 as supporting electrolyte and scan rate of 100 mV s-1. The analytical ...
Alexiu Viorica - - 2005
A method for the determination of total selenium in wheat and wheat flour using graphite furnace atomic absorption spectrometry (GFAAS) with palladium/ascorbic acid as a chemical modifier was studied. The effects of nickel nitrate, palladium/ascorbic acid, and palladium/magnesium nitrate as chemical modifiers on the sensitivity in the determination of selenite, ...
Martínez Sidonia - - 2005
Morrón pepper of 'Fresno de la Vega' (Capsicum annuum L.) is a big sweet variety cultivated in the province of León (northwestern Spain). Changes in vitamin C content of this variety of pepper as a function of ripeness, storage and different preservation systems were studied. The ascorbic acid content increases ...
Ali Esam H - - 2005
Vegetative growth of Saprolegnia parasitica decreased by increasing the concentration of NaCl and ascorbic acid. Under these conditions, the morphological features of the vegetative hyphae were distinguishable from those used as controls. NaCl and ascorbic acid in combination improved the tolerance of S. parasitica to high levels of salinity. Sporangial ...
Hachinohe Mayumi - - 2005
L-DOPA is an active allelochemical that inhibits plant growth. To determine whether the phytotoxicity is due to the reactive oxygen species generated during its oxidation to melanin, oxidative damage, melanin accumulation, and the effect of antioxidants on its phytotoxicity were examined in L-DOPA-tolerant (barnyard grass) and -susceptible (lettuce) plants, and ...
Peng Ying - - 2005
In this study, we established an embryo model to study the effects of ethanol on fetal development. When embryos of Xenopus laevis (the African clawed frog) were exposed to ethanol, the resultant tadpoles had significantly reduced brain sizes (microencephaly) and retarded growth rates. These effects, similar to those observed in ...
Brenes Carmen H - - 2005
The stability of red grape anthocyanins (Vitis vinifera) was evaluated in a model juice system during normal (25 degrees C) and accelerated storage (35 degrees C) in the presence of ascorbic acid. Rosemary polyphenolic cofactors (0, 0.2, and 0.4% v/v) were evaluated as anthocyanin stabilizing agents. Cofactor addition resulted in ...
Zeng Wenming - - 2005
A UV method for the analysis of ascorbic acid with methanol as solvent to prepare a sample has been developed and applied. The effect of copper(II) concentrations on the oxidation of ascorbic acid in aqueous solution has been studied in detail, and the regularities of ascorbic acid oxidation in methanol, ...
Johnston Carol S - - 2005
Ascorbic acid oxidizes in refrigerated orange juice, but the physiological relevance of this deterioration is unknown. We compared changes in plasma vitamin C and total lipid peroxides (thiobarbituric acid-reactive substances, TBARS) in the 2-hour period following consumption of commercial orange juices on day 1 vs day 8 of storage (4 ...
Hijova E - - 2005
BACKGROUND: Mercury is one of the ubiquitous pollutants participating in generation of reactive oxygen species leading to the formation of oxidative stress. METHODS: Changes in plasma concentrations of ascorbic acid and malondialdehyde were measured in rats after per os exposure to different doses of mercury (as mercuric chloride) for 30 ...
Wood Nelson - - 2005
The purpose of these experiments was to determine whether quantitative changes take place in the attached sugars of hepatic (postmitochondrial) glycoproteins isolated from rats fed a diet supplemented with citrus bioflavonoids (an equal mixture of rutin, naringin, and hesperidin) (B) and/or ascorbic acid (C) for 40 days and 90 days. ...
Wattanapitayakul Suvara K - - 2005
Doxorubicin is an important and effective anticancer drug widely used for the treatment of various types of cancer but its clinical use is limited by dose-dependent cardiotoxicity. Elevated tissue levels of cellular superoxide anion/oxidative stress are a mechanism by which doxorubicin-induced cardiotoxicity. Selected medicinal plant extracts were tested for their ...
Tao Zhongyan - - 2005
Reactive oxygen species (ROS) are believed to play a role in development of several diseases. L-ascorbic acid (AsA) is a kind of excellent antioxidant, but its instability in solution and hydrophilicity limits the wide use of it. Structural modifications of AsAby the introduction of lipophilic moieties can lead to derivatives ...
Kim So-Soon - - 2005
Acteoside extracted from the leaves of Rehmannia glutinosa was examined to determine the mechanism(s) of its antioxidant properties. The deoxyribose assay system showed that acteoside has a high redox potential as electron donor, which generates hydroxyl radicals in an Fe3+-dependent manner similar to ascorbic acid. However, the antioxidant properties of ...
Sakai Hiroyasu - - 2005
Sodium azulene sulfonate is a water-soluble derivative of azulene which is an antiinflammatory component of chamomile of the family of Asteraceae. Sodium azulene sulfonate is clinically used as a therapeutic agent in the treatment of pharyngitis as well as other inflammatory diseases such as tonsillitis, stomatitis and conjunctivitis. There has ...
Kleczkowski M - - 2005
The aim of the investigations was evaluation of ascorbic acia concentration in the blood or cows in the subclinical form of mastitis. The research was conducted on 56 cows. The cows were divided into 4 groups: A, B, and C with subclinical form of mastitis caused by Staphylococcus aureus, Streptococcus ...
Ray R C - - 2005
Sweetpotato storage roots are subjected to several forms of post harvest spoilage in the tropical climate during transportation from farmers' field to market and in storage. These are due to mechanical injury, weight loss, sprouting, and pests and diseases. Sweetpotato weevil is the single most important storage pest in tropical ...
Elmore Amy R - - 2005
L-Ascorbic Acid, Calcium Ascorbate, Magnesium Ascorbate, Magnesium Ascorbyl Phosphate, Sodium Ascorbate, and Sodium Ascorbyl Phosphate function in cosmetic formulations primarily as antioxidants. Ascorbic Acid is commonly called Vitamin C. Ascorbic Acid is used as an antioxidant and pH adjuster in a large variety of cosmetic formulations, over 3/4 of which ...
Logan Melissa Peasley - - 2005
OBJECTIVE: We have shown that acrolein, a lipid peroxidation byproduct, can inflict significant damage in isolated spinal cord white matter following oxygen glucose deprivation (OGD). The mechanism of such acrolein-induced damage is unclear. The aim of this study was to examine whether glutathione (GSH) and ascorbic acid, two reactive oxygen ...
Mahony D E - - 2005
Bismuth subsalicylate (BSS), the active ingredient of Pepto-Bismol, has been used for many years to treat various disorders of the gastrointestinal tract. Using mass spectrometry and the agar dilution method, we determined that insoluble BSS interacts with certain dietary components and organic substrates to produce water-soluble products with activity against ...
Hodosy Július J Institute of Physiology, Faculty of Medicine, and Department of Animal Physiology and Ethology, Faculty of Natural Sciences, Comenius University, Bratislava, Slovak - - 2005
Salivary thiobarbituric acid reacting substances (TBARS) have been previously shown to correlate with the impairment of gingival tissue. Although the details on the origin and the composition of this heterogeneous group of compounds in saliva are unknown, the potential clinical usefulness makes necessary the studies of factors influencing the salivary ...
Dalpiaz Alessandro - - 2005
Ascorbic acid (AA) or 6-Br-ascorbate (BrAA) conjugation has been investigated as a tool to improve brain drug delivery by the Vitamin C transporter SVCT2. To this aim, the effects of AA- or BrAA-conjugation on drug affinity and uptake have been assessed in vitro, by using human retinal pigment epithelium (HRPE) ...
Sowell John - - 2004
alpha,beta-Unsaturated aldehydes such as 4-hydroxy-2-nonenal (HNE) and other electrophilic lipid peroxidation (LPO) products may contribute to the pathogenesis of cancer, cardiovascular diseases, and other age-related diseases by cytotoxic, genotoxic, and proinflammatory mechanisms. The notion that vitamin C (ascorbic acid) acts as a biological antioxidant has been challenged recently by an ...
Corpe Christopher P - - 2005
Vitamin C intracellular accumulation is mediated by Na(+)-dependent vitamin C transporters SVCT1 and -2 and dehydroascorbic acid transporters GLUT1 and -3. It is unclear which pathways dominate in vivo. As a new step to resolve this issue, we identified and tested 6-bromo-6-deoxy-L-ascorbic acid as a specific candidate for SVCTs. In ...
Sainsbury Christopher A R - - 2004
Elevated circulating levels of NEFAs (non-esterified fatty acids) are associated with states of insulin resistance and increased risk of vascular disease. Previous animal and human studies have demonstrated NEFA-induced endothelial dysfunction of large conduit arteries, reversible by the antioxidant ascorbic acid. We therefore investigated the effect of NEFAs on carbachol-induced ...
Valpuesta Victoriano - - 2004
The biosynthetic pathway of L-ascorbic acid (vitamin C) in plants has been established for several years. However, recent reports describe alternative pathways, revealing a more complex picture of L-ascorbic acid biosynthesis than had been expected. GDP-L-gulose and myo-inositol are proposed as new intermediates in L-ascorbic acid biosynthesis, indicating that part ...
Chen Yanling - - 2004
A novel polymer modified electrode is discussed in this paper. This resulting electrode can catalyze remarkably toward the electrochemical oxidations of dopamine (DA) and ascorbic acid (AA). Moreover, it can clearly discriminate the electrochemical oxidations of DA from that of AA based on their semi-derivative voltammograms. Hence, a simultaneous determination ...
Messina Germán A - - 2004
The high sensitivity that can be attained using an enzymatic system and mediated by hydroquinone, has been verified by on-line interfacing of a rotating bioreactor and continuous flow/stopped-flow/continuous-flow processing. Horseradish peroxidase, HRP, [EC 1.11.1.7], immobilized on a rotating disk, in presence of hydrogen peroxide catalyses the oxidation of hydroquinone to ...
Leveque N - - 2004
BACKGROUND: Reactive oxygen species generated by ultraviolet light result in photocarcinogenic and photoaging changes in the skin. Antioxidants protect the skin from these insults. OBJECTIVE: The aim of this study was to determine the ex vivo ascorbic acid penetration and its degradation in the skin after its topical application from ...
Fluhr J W - - 2004
BACKGROUND: Cutaneous exposure to a variety of irritants has been extensively studied in recent years. Nevertheless, knowledge of the induction of irritant dermatitis, especially by mild irritants at low doses and for a short duration of exposure, is still incomplete. OBJECTIVES: To quantify the irritant effects and barrier disruption properties ...
Lee Yong-Wha - - 2004
BACKGROUND: The haptoglobin (Hp) 2-2 phenotype has been known to have less antioxidative activity than Hp 1-1 and Hp 2-1. However, few have reported the relationship between oxidative stress and Hp phenotypes by using oxidized LDL. The relationship between Hp phenotypes and oxidative stress was therefore investigated in healthy adults. ...
Patak P - - 2004
The adrenal gland is among the organs with the highest concentration of vitamin C in the body. Interestingly, both the adrenal cortex and the medulla accumulate such high levels of ascorbate. Ascorbic acid is a cofactor required both in catecholamine biosynthesis and in adrenal steroidogenesis. Here we provide an overview ...
Bell Christopher - - 2005
Maximal aerobic capacity (Vo(2max)) decreases progressively with age, primarily because of a reduction in maximal cardiac output (Q(max)). This age-associated decline in Vo(2max) may be partially mediated by the development of oxidative stress that can suppress beta-adrenergic-receptor responsiveness and, consequently, reduce Q(max). To test this hypothesis, Vo(2max) (indirect calorimetry) and ...
Olabisi Ayodele O - - 2004
l-Ascorbic acid is a versatile radical scavenger widely distributed in aerobic organisms that plays a central role in the protection of cellular components against oxidative damage by free radicals and oxidants. It also functions as a physiological reductant for key enzymatic transformations in catecholamine neurotransmitters, amidated peptide hormones, and collagen ...
Manfredini Stefano - - 2004
Preliminary investigations allowed us to anticipate that conjugation of nipecotic acid with L-ascorbate (AA) gave a prodrug endowed with anticonvulsant activity in mice. In view of these results, and in order to get deepen insight into the molecular aspects at the base of the transport mechanism, a second generation of ...
Dereköy Fevzi Sefa - - 2004
OBJECTIVES/HYPOTHESIS: The objective was to investigate the effects of both noise exposure and ascorbic acid on oxidative status and hearing thresholds of rabbits. STUDY DESIGN: Randomized prospective animal study comparing oxidative parameters and otoacoustic emissions in two rabbit groups exposed to noise. One group was given ascorbic acid, the other ...
Viscovich Michael - - 2004
BACKGROUND & AIMS: Combination of the antioxidants ascorbic acid in slow release formulation and alpha-tocopherol can retard the progression of atherosclerosis. In order to determine if differences in formulation could explain some of the different results in the intervention trials we determined selected pharmacokinetics for two different formulations of ascorbic ...
Heckelen A - - 2004
PURPOSE: Proliferation control in adult retinal pigment epithelial (ARPE) cells is an essential factor in the clinical management of proliferative vitreoretinopathy (PVR). Factors which inhibit PVR and which are without toxic potential are therefore of interest in controlling proliferation. The aim of the present study was to gain insight into ...
Prauchner Carlos André - - 2004
We investigated whether intrastriatal (i.s.) administration of 5-aminolevulinic acid (ALA) induces oxidative damage and whether behavioral alterations induced by i.s. administration of ALA could be affected by antioxidants. Unilateral injection of ALA (6 micromol/striatum) increased (approximately 30%) thiobarbituric acid-reactive substances (TBARS), but did not affect striatal content of total thiol ...
Malinauskas A - - 2004
The present short review deals with electroanalytical aspects of electrochemical response of ascorbic acid (Vitamin C) at conducting and electrogenerated polymer modified electrodes. Two main topics are considered: (i) electrocatalytic oxidation of ascorbate at conducting polymer modified electrodes, leading to electroanalytical techniques for ascorbate assay, and (ii) retardation of ascorbate ...
Anastos Nicole - - 2004
The limits of detection (3s) for ascorbic acid were 5x10(-8)M with acidic potassium permanganate using both flow injection analysis (FIA) and sequential injection analysis (SIA) whereas the soluble manganese(IV) afforded 1x10(-8)M and 5x10(-9)M for FIA and SIA, respectively. Determinations of ascorbic acid in Vitamin C tablets were achieved with minimal ...
Ogawa Yoshihide - - 2004
Ascorbic acid overload and vitamin B6 deficiency have been implicated in the development of hyperoxalemia in dialysis patients, but there is still disagreement about this. Hemodialysis patients who are exposed long-term hyperoxalemia may develop secondary oxalosis with an increased risk of cardiac, vascular, and bone disease, and thus may benefit ...
Kim S Samuel - - 2004
OBJECTIVE: To estimate ischemic tissue damage in ovarian cortex and to evaluate the effectiveness of ascorbic acid, an antioxidant, to protect ovarian tissue from apoptosis caused by ischemia. DESIGN: In vitro laboratory experiments. SETTING: Academic research institute. INTERVENTION(S): Fresh and frozen/thawed cortical sections of bovine ovaries were incubated in MEM ...
Shin Dong-Mi - - 2004
Ascorbic acid has been reported to enhance differentiation of embryonic stem (ES) cells into neurons, however, the specific functions of ascorbic acid have not been defined yet. To address this issue, gene expression profiling was performed using cDNA microarray. Ascorbic acid increased the expressions of genes involved in neurogenesis, maturation, ...
Ma Yi Long - - 2004
Distribution of ascorbate into tissues is an essential process in ascorbate antioxidant defense. Hibernating animals are studied as a model of tolerance to ischemia-reperfusion because of their tolerance to fluctuations in blood flow associated with prolonged torpor and periodic arousal episodes. Throughout hibernation, plasma ascorbate concentration ([Asc](p)) repetitively increases during ...
Abdulmajed Kasem - - 2004
A novel synthetic technique was used to synthesise the co-drug retinyl ascorbate (RA-AsA) ester from all-trans-retinyl chloride (RA) and L-ascorbic acid (AsA) suspended in ethanol at low temperature. Its log P, solubility in a Me:PBS, 50/50 at pH 4.8 and degradation constant were determined. The flux and permeation coefficient were ...
Geracitano L A - - 2004
Laeonereis acuta (Polychaeta, Nereididae) was collected in an unpolluted (UP) and an polluted (P) site at the Patos Lagoon estuary (Southern Brazil) and maintained under control conditions (UPC and PC, respectively) or exposed to waterborne copper (UPCu and PCu; 500 microg Cu/l), for 48 h. Four groups (aaUPC, aaPC, aaUPCu, ...
Nisha P - - 2004
The kinetics of ascorbic acid degradation in amla (Phyllanthus emblica L.) as well as in pure ascorbic acid solutions at initial concentrations present in amla over a temperature range of 50-120 degrees C (steady-state temperature) has been studied. The ascorbic acid degradation followed first-order reaction kinetics where the rate constant ...
Kuo Shiu-Ming - - 2004
Under the cell-free condition, copper is known to oxidize ascorbic acid (the active form of vitamin C) and the event leads to the loss of vitamin C. However, the biological consequence of this interaction was never examined in the presence of cells. We demonstrated in intestinal epithelial cells that dehydroascorbic ...
Espinal-Perez Liliana Elizabeth - - 2004
BACKGROUND: Melasma is an acquired treatment-resistant hyperpigmentation of the skin. METHODS: Sixteen women with idiopathic melasma were included in our trial. After randomization by another clinician, they were instructed to use, at night, 5% ascorbic acid cream on one side of the face and 4% hydroquinone cream on the other ...
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