Lower Ascorbic Acid Content Research Articles

High Iron and Low Ascorbic Acid Concentrations in the Dermis of Atopic Dermatitis Patients

Background: Atopic dermatitis (AD) is a chronic inflammatory skin disease in which reactive oxygen species (ROS) may be involved. Iron catalyses ROS formation and ascorbic acid (AA) scavenges these species. Objective: The aim of this work was to determine iron and AA levels in AD patients’ dermis and to compare their concentrations with those of healthy volunteers’ dermis. Methods: Five AD patients and 5 healthy subjects (controls) were enrolled in this study. Iron and AA were collected from human dermis by microdialysis and assessed by atomic absorption spectrometry and gas chromatography-mass spectrometry, respectively. Results: The AD dermis demonstrated higher iron concentrations (44.3 ± 4.6 µg/l) compared to controls (21.8 ± 1.2 µg/l) as well as a significantly lower concentration of AA (46.7 ± 0.6 vs. 176.8 ± 14.5 µg/ml, respectively). Conclusion: These results suggest that iron and AA dermis levels could be indicators of inflammatory tissues and might be implicated in dermatological diseases such as AD.

Ascorbic-acid transporter Slc23a1 is essential for vitamin C transport into the brain and for perinatal survival.

The only proven requirement for ascorbic acid (vitamin C) is in preventing scurvy, presumably because it is a cofactor for hydroxylases required for post-translational modifications that stabilize collagen. We have created mice deficient in the mouse ortholog (solute carrier family 23 member 1 or Slc23a1) of a rat ascorbic-acid transporter, Svct2 (ref. 4). Cultured embryonic fibroblasts from homozygous Slc23a1(-/-) mice had less than 5% of normal ascorbic-acid uptake. Ascorbic-acid levels were undetectable or markedly reduced in the blood and tissues of Slc23a1(-/-) mice. Prenatal supplementation of pregnant females did not elevate blood ascorbic acid in Slc23a1(-/-) fetuses, suggesting Slc23a1 is important in placental ascorbic-acid transport. Slc23a1(-/-) mice died within a few minutes of birth with respiratory failure and intraparenchymal brain hemorrhage. Lungs showed no postnatal expansion but had normal surfactant protein B levels. Brain hemorrhage was unlikely to be simply a form of scurvy since Slc23a1(-/-) mice showed no hemorrhage in any other tissues and their skin had normal skin 4-hydroxyproline levels despite low ascorbic-acid content. We conclude that Slc23a1 is required for transport of ascorbic acid into many tissues and across the placenta. Deficiency of the transporter is lethal in newborn mice, thereby revealing a previously unrecognized requirement for ascorbic acid in the perinatal period.

Effect of heat treatment and controlled atmosphere on quality of fresh-cut tomatoes.

Fresh-cut tomato fruits at pink stage of ripening were heat treated at 35°C for 6 hr and were stored in perforated polyethylene packages at 2°C in air or controlled atmosphere (2.5% O 2 and 5% CO 2 ) for six or twelve days. Weight loss, chlorophyll and lycopene contents, seed discoloration, fungal infection, total soluble solids content, titratable acidity, sugar/acid ratio, pH, taste, firmness, ascorbic acid content, rate of respiration and ethylene production, and electrolyte leakage were evaluated after each storage period. Heat-treated slices had greater weight loss, minimum seed discoloration, less chlorophyll, higher total soluble solids and ascorbic acid content, better taste, and lower rates of respiration and ethylene production, lower titratable acidity content, and higher electrolyte leakage than unheated slices. The overall quality of controlled atmosphere-stored slices was better than that of air-stored slices. Prolonged storage resulted in increased weight loss, seed discoloration, pH, titratable acidity, rate of respiration and off-flavor, lower chlorophyll and lycopene content, and lower total soluble solids, sugar/acid ratio, and ascorbic acid content.

Stabilization of Tc-99m radiopharmaceuticals by chemical additives

The reliability and applicability of the preparation of the three, for nuclear medicine very important, 99mTc-radiopharmaceuticals from the inactive (technetium-cold) kit solutions were tested. Each examined commercial kit was dissolved in saline (0.9% NaCl). The conditions of the storage of the inactive kit solutions till labeling were examined. The main problem is the stablity of the reductant stannous ions which is very difficult to predict. To stabilize and ensure a good quality of the labeled radiopharmaceuticals, ascorbic or gentisic acid were added. It was found that the best results were obtained by keeping the samples frozen at -20?C. Both stabilizers can be used but for an effective protection much lower concentrations of ascorbic acid are needed. Its concentrations of 12-60 ?g/ml of the kit, stabilized dimercaptosuccinate (DMS) and pyrophosphate (PyP) for about 7-8 days. The solution of 2,3-dicarboxypropane- 1,1-diphosphonate (DPD) was found to be stable even without the stabilizer. This could be attributed probably to the chemical nature of this complex. However, in routine praxis the applied procedure demands great care and personel very experienced in radiopharmacy.

Ascorbate prevents the interaction of superoxide and nitric oxide only at very high physiological concentrations.

The bioactivity of nitric oxide (.NO) depends, in part, on its interaction with superoxide. Usually, superoxide dismutase (SOD) preserves .NO bioactivity by limiting the availability of superoxide. Ascorbic acid also effectively scavenges superoxide, but the extent to which this interaction is necessary for intact .NO bioactivity is not known. Therefore, the present study examined the effect of ascorbic acid on .NO bioactivity with isolated rabbit arterial segments. A steady flux of superoxide (1.15 to 2.3 micromol . L-1 . min-1) produced either by pyrogallol autoxidation or a hypoxanthine/xanthine oxidase system inhibited endothelium-derived .NO-mediated arterial relaxation elicited by acetylcholine. This effect of superoxide was completely blocked by SOD (300 IU/mL) and the manganese SOD mimic EUK-8 (300 micromol/L) and partially inhibited by ascorbic acid (10 mmol/L). Lower concentrations of ascorbic acid were ineffective despite scavenging >90% of superoxide. We increased the endogenous flux of superoxide (3.2+/-0.3-fold) by inhibiting vascular copper-zinc SOD with diethyldithiocarbamate. This increased endogenous flux of superoxide produced an impairment of .NO-mediated arterial relaxation that was reversed by EUK-8 (300 micromol/L) but not ascorbic acid (10 mmol/L) despite equivalent scavenging of the endogenous superoxide flux. We used 3-nitrotyrosine formation (from peroxynitrite) as an indicator of .NO interaction with superoxide and found that SOD and EUK-8 compete more effectively with .NO for superoxide than does ascorbic acid. These data indicate that preservation of .NO bioactivity by superoxide scavengers depends not only on superoxide scavenging activity, but also on the rate of superoxide scavenging. Normal extracellular concentrations of ascorbic acid (30 to 150 micromol/L) are not likely to prevent the interaction of .NO with superoxide under physiological conditions.

Long-term effects of several biochemical and physical factors on cellulose biosynthesis in callus and suspension cultures of normal and mutant barley (Hordeum vulgare L.) strains producing less cellulose

To clarify a low level of cellulose biosynthesis of thein vitro cultured cells, the effects of several biochemical factors such as carbon sources (sucrose, maltose, and UDPG), antioxidants (ascorbic acid and glutathione) and physical factors such as artificial pressure, high gravity, on the cellulose production in barley callus and suspension cultures were investigated. In the suspension culture of two barley strains, the supplement of different concentrations (0, 1.5, 3.0, and 4.5%) of sucrose or maltose into the medium for 30 days did not promote the cellulose production and 4.5% of sugar supplement was rather inhibitory in one strain. However, in the presence of sucrose at 3%, UDPG (3 or 10 mM) supplement, as a precursor for cellulose, promoted 1.2–13 fold of the production in two strains. A low concentration (3 mM) of ascorbic acid and glutathione promoted 1.5 and 1.2 fold of the production in two strains, respectively. These results suggest that low cellulose biosynthesis of thein vitro cultured cells is due to a decreased level of the UDPG in the cytosol, and that the oxidative condition of external medium impedes cellulose synthesis in some manners. Artificial pressure applied to the callus promoted 1.4 fold of the cellulose production. High gravity (5,000 or 10,000g) applied to the suspension-cultured cells by centrifugation did not cause a substantial change.

Determination of ascorbic acid in human vitreous humor by high-performance liquid chromatography with UV detection

PURPOSE. Ascorbic acid (AA) accumulates in vitreous at a concentration several times higher than in plasma. It has been suggested that AA may serve as an antioxidant that protects ocular tissues from free radical attack. There are many reports about the concentration of AA in ocular tissues. However, AA in adult human vitreous humor has not been determined. We measured concentrations of AA from pathologic human vitreous samples and compared the results. METHODS. AA was measured by high-performance liquid chromatography (HPLC) with UV detection. Human vitreous humor was collected from patients undergoing pars plana vitrectomy. RESULTS. AA was quantified in vitreous humor of proliferative diabetic retinopathy (PDR), proliferative vitreoretinopathy (PVR), macular hole (MH), idiopathic premacular fibrosis (PMF), and Terson syndrome (Terson). The concentrations of AA were 120.9 ± 36.3 mg/ml (mean ± SD), 129.8 ± 36.6, 311.5 ± 126.7, 446.9 ± 154.2 and 406.0 ± 22.0, respectively. There was no significant difference between the PDR and the PVR groups (unpaired t-test). Patients with PDR and PVR showed significantly lower concentrations of AA than those with MH, PMF, and Terson (p < 0.01). CONCLUSIONS. These findings suggest that increased oxidative stress may be produced in the ocular tissues of eyes with PDR and PVR, and AA appears to be consumed (oxidized) in performing its protective role.

Meeting the Iron Needs of Infants and Young Children

Meeting the Iron Needs of Infants and Young Children

Vitamin C supplementation and fear-reduction in Japanese quail: short-term cumulative effects.

1. Fear-related behaviour was measured in individually-housed Japanese quail which had received either untreated drinking water (UDW) or a vitamin C solution (ascorbyl-2-polyphosphate, APP, 1 g L-ascorbic acid/1 for 1 or 4 d. Behavioural tests were carried out at 24 or 27 d of age. Water consumption was measured daily and plasma ascorbic acid (AA) content was assayed after differential treatment for 1 or 4 d. 2. The quail in the APP treatment groups drank significantly more than did those receiving untreated drinking water. 3. Supplementation with APP raised plasma AA concentrations substantially above those found in UDW quail. The lower AA concentrations found after APP treatment for 4 d rather than one may have reflected either inter-assay variation or limited intestinal absorption following excess ingestion. 4. Quail treated with APP showed less home-cage avoidance of a novel object and shorter tonic immobility fear reactions than did the UDW birds. The UDW quail showed remarkably similar avoidance and TI scores on test days 1 and 4. Conversely, continued treatment with APP further reduced avoidance scores but, although TI durations fell slightly with continued treatment there were no significant day effects. 5. It was concluded that APP supplementation can reduce underlying fearfulness but that it may not be necessary to continue treatment for longer than 24 h immediately prior to a known frightening event.

Ascorbic acid/saline eluant increases 188Re yields after “wet” storage of 188W/ 188Re generators

We have evaluated several factors in an attempt to minimize the reduced yields observed after “wet” storage of 188W/ 188Re generators, which include the dispersion of 188W-tungstic acid in the alumina column bed by pre-mixing with silica gel, incorporation of cupric ion as an antioxidant in the adsorbent, and elution of the alumina columns with saline solution containing ascorbic acid. The results demonstrate that dispersion of the 188W-tungstic acid in a silicaalumina bed and the use of cupric ion do not significantly increase 188Re yields after weekend “wet” storage. In contrast, addition of ascorbic acid at concentrations as low as 0.01% in the saline eluant was found to be an effective method of maintaining good 188Re yields after “wet” weekend storage, resulting in Monday elution yields greater than 70%. Use of low concentrations of ascorbic acid is thus an effective alternative to drying the generator columns before storage.

Oxidative modification and antioxidant protection of human low density lipoprotein at high and low oxygen partial pressures

Oxidative modification of low density lipoprotein (LDL) in the subendothelial space of the arterial wall has been implicated as an initial process in atherosclerosis. In vitro studies of LDL oxidation are usually done at ambient oxygen partial pressure (pO2; approximately 160 torr, or 21% O2), which is considerably higher than arterial tissue pO2 (30-70 torr, and as low as 20 torr, or 2.5% O2, in atherosclerotic lesions). In addition, beta-carotene acts as an efficient free radical scavenger only at low pO2. Therefore, we investigated the effects of high (20%) and low (2%) pO2 on the kinetics of LDL oxidation, and the effectiveness of beta-carotene compared to other physiological antioxidants in preventing LDL oxidation. At low pO2, the rate of Cu(2+)-induced oxidative modification of LDL was lower than at high pO2. Furthermore, at high pO2 there was a distinct lag phase preceding the propagation phase of lipid peroxidation in Cu(2+)-exposed LDL, as measured by cholesteryl ester hydroperoxide formation; in contrast, there appeared to be no distinct lipid peroxidation lag phase in LDL incubated with Cu2+ at low pO2. Elevating alpha-tocopherol levels in LDL about 5-fold resulted in significant antioxidant protection: the lipid peroxidation lag phase at high pO2 increased by 45% (from 58 +/- 11 to 84 +/- 3 min, P < 0.05), and the initial rate (0-1 h) of lipid hydroperoxide formation at low pO2 was reduced by 52% (from 11.6 +/- 1.9 to 5.6 +/- 1.0 nmol/mg LDL protein/h, P < 0.01). In contrast, increasing LDL beta-carotene levels about 6-fold did not inhibit LDL oxidation at either pO2. Most remarkably, low concentrations of ascorbic acid (30 microM) drastically reduced LDL oxidation, regardless of pO2: the lipid peroxidation lag phase at high pO2 increased more than 7-fold (from 46 +/- 11 min to > 360 min, P < 0.001), and at low pO2 no lipid hydroperoxides could be detected for at least 6 h of incubation. These results show that at low physiological pO2, Cu(2+)-induced LDL oxidation occurs at a significantly lower rate than at ambient pO2. At both high and low pO2, beta-carotene cannot inhibit LDL oxidation, whereas alpha-tocopherol has a moderate protective effect, and low physiological concentrations of ascorbic acid very strongly suppress LDL oxidation.

Exercise and tissue ascorbic acid content in guinea pigs

The effects of treadmill exercise (20 m/min, five days/wk, one hr/day) on growth and tissue ascorbic acid (AA) concentrations were investigated in 40 young, male guinea pigs. Animals were fed ad libitium an AA-free diet which was supplemented with AA. AA was administered daily via gavage feeding. Animals were divided into two groups, exercise (E) and sedentary (S). Food consumption and body weight were recorded. After eight weeks, animals were sacrificed and blood taken via heart puncture. Liver, spleen, adrenals and kidneys were removed, weighed and frozen. Plasma and organ tissues were analyzed for AA. Results indicated that exercise had no significant effect on growth. Growth was within normal range. Exercised animals had significantly (p<0.05) lower AA concentrations in liver (E, 3.29±0.63; S, 3.73±0.58 mg/100 g, mean±SD) and adrenal (E, 18.06±5.41; S, 21.98±7.88 mg/100 g) tissue as compared with sedentary guinea pigs. In summary, moderate running significantly reduced the AA concentration of liver and adrenal glands. These results suggest that AA requirement may be increased with moderate exercise.

Helicobacter pylori-associated gastritis and the ascorbic acid concentration in gastric juice.

Patients infected with Helicobacter pylori have abnormally low ascorbic acid concentration in gastric juice. Low vitamin C intake and Helicobacter pylori infection have been related to an increased risk of gastric carcinoma. This report examines the association between ascorbic acid and Helicobacter pylori in patients referred for upper gastrointestinal endoscopy. Elevated gastric pH and the damage to the gastric surface epithelium were inversely associated with the ascorbic acid concentration in gastric juice. We postulate that these two factors mediate the ascorbic acid-decreasing effect of Helicobacter pylori. Patients with nonpremalignant conditions (normal gastric histology, diffuse antral gastritis, or duodenal ulcer) had lower gastric pH, less damage to the gastric epithelium, and higher levels of ascorbic acid in gastric juice than patients with atrophic gastritis, intestinal metaplasia, or dysplasia.

EFFECT OF PACKAGING MATERIAL ON THE QUALITY OF POTATOES TREATED WITH ISOPROPYL N‐(3‐CHLOROPHENYL) CARBAMATE (CIPC)

ABSTRACTKatahdin and Russet Burbank potatoes, treated with isopropyl N‐3(‐chlorophenl) carbamate CIPC and stored for four months at 5C in either mesh or polyethylene bags (two packaging materials frequently used for potato storage), were tested for enzymatic discoloration, phenolic and ascorbic acid concentration. CIPC residues in tubers stored in polyethylene bags were significantly (p &lt; 0.0l) higher than those stored in mesh bags. Tubers stored in polyethylene showed significantly (p&lt;0.05) higher discoloration and phenolic concentration, and lower ascorbic acid concentration than those stored in mesh bags. Differences in CIPC retention of the tubers stored in the two packaging materials may have been responsible for some of the differences in quality factors since CIPC was shown to significantly (p&lt;0.0l) increase the enzymatic discoloration and phenolic concentration, and decrease the ascorbic acid concentration of both cultivars.

Ascorbic acid oxidation: A potential cause of the elevated severity of atherosclerosis in diabetes mellitus?

The exposure of mouse peritoneal macrophages to cholesterol linoleate-containing, artificial lipoproteins can lead to intracellular ceroid accumulation. This can be used as a model to study the role of oxidation in macrophage uptake of lipoproteins containing unsaturated fatty acids, considered by many as a primary event in atherosclerotic plaque formation. Our studies show that ascorbic acid can both inhibit and promote the formation of ceroid in such a model system. The transition metal copper (Cu(II)) further elevates ceroid accumulation and EDTA, a metal chelator, inhibits it. When trace levels of transition metals are present, low concentrations of ascorbic acid can elevate ceroid formation. This pro- and antioxidant characteristic of ascorbic acid was confirmed by monitoring the generation of oxidants by various concentrations of ascorbic acid, assessed by benzoic acid hydroxylation or the fragmentation of BSA. We discuss these observations in the context of an apparent increase in ascorbic acid oxidation and elevated severity of atherosclerosis in diabetes mellitus.

Dissolution Kinetics of Nickel Ferrite in Amino Poly Carboxylic Acids

Nickel ferrite is one of the important corrosion products of PHWR's where Monel and carbon steel are used as the constructional materials in the primary heat transport system. The dissolution of synthetically prepared nickel ferrite was studied in low concentrations (<10 mmol/l) of HEDTA, DTPA, NTA and HIDA. The dependence of the dissolution rate on the ligand concentration was found to be langmuirian in all these cases. The effect of the addition of low concentrations of citric acid, oxalic acid, ascorbic acid and Fe(II)-ligand complex, individually, to each of the above chelating agents was also studied. The effect of pH and temperature on the dissolution rate was determined.

Dissolution Kinetics of Nickel Ferrite in Chelating and Reducing Agents

As a first step towards developing a decontaminating solution, the dissolution of synthetically prepared nickel ferrite was studied in low concentrations (<l g/l of EDTA and oxalic acid individually and in combination. The ratio of the molar concentration of the ligand to that of the total iron dissolved was varied from 1 to 4. The dependence of the rate was linear in the case of EDTA and Langmurian in the case of oxalic acid. The effect of addition of low concentrations of citric acid, formic acid, ascorbic acid and Fe(II)-EDTA to EDTA solutions was also studied. The effect of pH in the range of 1.4–8.7, on the kinetics of dissolution in EDTA and oxalic acid medium was also determined.

Disturbed handling of ascorbic acid in diabetic patients with and without microangiopathy during high dose ascorbate supplementation

Abnormalities of ascorbic acid metabolism have been reported in experimentally-induced diabetes and in diabetic patients. Ascorbate is a powerful antioxidant, a cofactor in collagen biosynthesis, and affects platelet activation, prostaglandin synthesis and the polyol pathway. This suggests a possible close interrelationship between ascorbic acid metabolism and pathways known to be influenced by diabetes. We determined serum ascorbic acid and its metabolite, dehydroascorbic acid, as indices of antioxidant status, and the ratio, dehydroascorbate/ascorbate, as an index of oxidative stress, in 20 matched diabetic patients with and 20 without microangiopathy and in 22 age-matched control subjects. Each study subject then took ascorbic acid, 1 g daily orally, for six weeks with repeat measurements taken at three and six weeks. At baseline, patients with microangiopathy had lower ascorbic acid concentrations than those without microangiopathy and control subjects (42.1 +/- 19.3 vs 55.6 +/- 20.0, p less than 0.01, vs 82.9 +/- 30.9 mumol/l, p less than 0.001) and elevated dehydroascorbate/ascorbate ratios (0.87 +/- 0.46 vs 0.61 +/- 0.26, p less than 0.01, vs 0.38 +/- 0.14, p less than 0.001). At three weeks, ascorbate concentrations rose in all groups (p less than 0.0001) and was maintained in control subjects (151.5 +/- 56.3 mumol/l), but fell in both diabetic groups by six weeks (p less than 0.01). Dehydroascorbate/ascorbate ratios fell in all groups at three weeks (p less than 0.0001) but rose again in the diabetic groups by six weeks (p less than 0.001) and was unchanged in the control subjects. Dehydroascorbate concentrations rose significantly from baseline in all groups by six weeks of ascorbic acid supplementation (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Determination of glutathione, glutathione disulphide, ascorbic acid and dehydroascorbic acid in tissues by reversed-phase liquid chromatography with electrochemical detection

High-performance liquid chromatography with electrochemical detection was applied to the estimation of glutathione, glutathione disulphide, ascorbic acid and dehydroascorbic acid in various tissues of man, animal, and plant. The simultaneous determination of glutathione and ascorbic acid in tissues was done by a coulometric method. Separation of glutathione and ascorbic acid and unequivocal substance identifications were performed on a 100×4.6 mm RP-18 Spheri 5 column. As mobile phase 0.015 mol/l o-phosphoric acid, pH 2.3 was used. Retention time of ascorbic acid was 5.0 min and of glutathione 10.0 min. Dehydroascorbic acid was determined after reduction to ascorbic acid with dithiothreitol. Glutathione disulphide was reduced at pH 7.5 by β-nicotinamide-dinucleotide phosphate and glutathione reductase, EC 1.6.4.2., to regenerate glutathione. To exclude interfering substances, several other compounds present in tissues and foods were investigated. This coulometric method is highly sensitive, specific and simple. Very low concentrations of ascorbic acid, glutathione, dehydroascorbic acid, and glutathione disulphide (<500 pg/injection) could be analysed using this HPLC-ECD method.

Field assessment of biomarkers for winter flounder

Winter flounder, Pseudopleuronectes americanus, from Boston Harbor near the Deer Island sewage outfall and from a nearby reference population near Plymouth Beach, Massachusetts, USA, were collected on several occasions and analysed for a variety of biochemical variables and histopathological conditions. A number of biochemical variables including hepatic and pectoral fin ascorbic acid concentrations, hepatic glycogen and lipid levels, plasma glucose concentrations, brain serotonin and norepinephrine concentrations, and the concentration and ratio of various free amino acids in muscle tissue were significantly different between the two populations. The apparent apoptotic hepatic lesions were found in the majority of the winter flounder collected from Boston Harbor and were rarely observed in animals from the reference site. Low tissue concentrations of ascorbic acid and hepatic glycogen were found to have significant statistical associations with the presence and degree of severity of these hepatic lesions.