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PubMed1990

Effect of environmental stress on the ascorbic acid requirement of laying hens.

An experiment with a factorial arrangement of treatment (3 by 2 by 2 by 2) was conducted to determine the effect of ascorbic-acid supplementation (0, 100, and 200 ppm) on the performance of two commercial layer strains housed at a density of either 3 or 4 birds per cage and relative humidities (RH) of 40% or 60%. The hens were subjected to a continuous heat stress of 31.1 degrees C for the 3-mo experimental period. As a comparison with an unstressed control group, an additional group of hens was housed at 23.9 degrees C and 40% RH and was fed the diet without ascorbic-acid supplementation. Mortality was reduced by ascorbic-acid supplementation. Shell weight per unit surface area showed a small increase with the added ascorbic acid. Values (in Haugh units) were increased by ascorbic-acid supplementation at the 200 ppm level and by the lower relative humidity. The higher RH reduced egg production by 4.16% and changed feed efficiency from 2.29 to 2.45 g of feed intake per gram of egg mass. There were differences in blood pH, blood CO2, blood HCO3-, and blood and adrenal ascorbic-acid levels due to the housing temperature. The higher RH produced blood-chemistry changes that were typical of respiratory alkalosis, which has been shown to occur in layers at high temperatures. Higher cage density, on the other hand, showed no change in the HCO3 level; but blood pCO2 was increased while blood pH was decreased. These results demonstrate that ascorbic-acid supplementation can be effective in reducing laying-hen mortality due to environmental stress and has small influences on egg quality.

Adrenal Glands↗

PubMed2002

A simple, inexpensive, and precise spectrophotometric method for evaluating the concentration of ascorbic acid in CSF samples: data from different neurological pathologies.

A method is presented for evaluating the concentration of ascorbic acid in 10 microliters samples of cerebrospinal fluid (CSF) with just ultraviolet (UV) scanning in the 220-300 nm range. The method assumes that the two main UV absorbing CSF components are proteins (with a peak at 280 nm) and ascorbic acid (with a peak at 264 nm). On this basis, the absorbances at those wavelengths are the starting points for a calculation that evaluates the sheer contribution of ascorbic acid to the absorbance at 264 nm. The rapidity of the UV analysis (just a few min), together with the precaution of keeping the samples under argon, along the short preparatory procedure, is especially suitable in the analysis of an air labile substance, such as ascorbic acid. The results of the UV procedure have been checked with parallel HPLC determinations for 19 test CSF samples and the results have shown an excellent correspondence. Finally, data are presented about the evaluation of ascorbic acid concentrations in CSF samples from various neurological pathologies in comparison with normal cases. These data show the interesting result of a significant reduction in the average ascorbic acid CSF level in patients suffering from Alzheimer's disease. However, a decrease in that parameter is found also for a few other pathologies.

Ascorbic Acid↗

PubMed1976

The effect of ascorbic acid on production of human interferon and the antiviral activity in vitro.

The effects of ascorbic acid on interferon production and on the antiviral effect of interferon in cultures of human cells were investigated. Ascorbic acid enhanced the interferon levels produced by human embryo skin and human embryo lung fibroblasts, induced by Newcastle disease virus and by polyinosinic-polycytidylic acid. The same concentrations of ascorbic acid had no effect on interferon production in two lymphoblastoid cell lines induced by Sendai virus. Leucocyte interferon assayed in lung fibroblasts titrated 0.2-0.3 log10 units higher in the presence of 5 mug ascorbic acid than in the absence of the latter.

Ascorbic Acid↗

PubMed1990

Effect of ascorbic acid on plasma alcohol clearance.

The effects of short-term and long-term ascorbic acid supplements on plasma alcohol clearance were studied in 13 clinically healthy male subjects. Two dose levels of alcohol, 0.5 and 0.8 g/kg body weight, were used. Blood samples were taken at zero time, 0.5 hours, then hourly up to 6 hours after alcohol consumption for the measurement of plasma alcohol and ascorbic acid levels, red-cell reduced glutathione level, and plasma alanine aminotransferase activity. At both dosages of alcohol, short-term as well as long-term pretreatment with ascorbic acid significantly enhanced the clearance of plasma alcohol. Although long-term ascorbic acid pretreatment resulted in better alcohol clearance, no significant difference in alcohol clearance was found between short-term and long-term ascorbic acid pretreatment. The two dose levels of alcohol had no significant effect on the red-cell reduced glutathione concentration or plasma alanine aminotransferase activity.

Adult↗

PubMed2001

Combined effect of ascorbic acid and gamma irradiation on microbial and sensorial characteristics of beef patties during refrigerated storage.

The present study was undertaken to evaluate the effect of ascorbic acid concentrations (0.03 to 0.5%) and irradiation doses (0.5 to 4 kGy) on microbial growth, color coordinates (L, a, and b), and sensory characteristics (taste and odor) of beef patties during storage at 4 +/- 1 degrees C. Ascorbic acid was also compared to citric acid at a similar pH value in order to differentiate the effects of ascorbic acid from those of pH reduction. Results showed significant reduction (p< or = 0.05) of aerobic plate counts (APCs) and total coliforms, and a significant interaction (p< or = 0.05) between ascorbic acid and irradiation dose was observed. The irradiation treatment had detrimental effects on redness, yellowness, and hue angle values of meat. However, incorporation of ascorbic acid into the meat before irradiation resulted in significant (p< or = 0.05) stabilization of color parameters. The color improvement obtained with ascorbic acid was not related to the pH reduction. Also, no significant detrimental effect on taste or odor was found in irradiated samples containing ascorbic acid.

Animals↗

PubMed1984

Dietary ascorbic acid deficiency in guinea pigs: no effect on ethanol preference, spiroperidol binding, or monoamine oxidase activity.

Ascorbic acid levels are commonly reported to be decreased in alcoholics. Although this deficiency could be due to dietary factors, there is evidence that ascorbic acid may be involved in the metabolism and acute effects of ethanol, possibly related to the pathogenesis of alcoholism. Therefore, we examined ethanol preference in guinea pigs receiving an ascorbate deficient vs a normal diet. Brain and spleen ascorbic acid levels were dramatically decreased, but ethanol preference was not altered by the acute dietary deficiency of this vitamin. In addition, an acute stressor (cold water swim), alone or in combination with ascorbate deficiency, had no effect on ethanol preference. At termination of the experiment, two measures of brain aminergic function (MAO activity and 3H-spiroperidol binding), purportedly altered by ethanol or ascorbic acid or both, were not associated with tissue ascorbate levels.

Alcohol Drinking↗

PubMed1986

Effect of ascorbic acid on calcium elimination in humans.

The long-term and short-term influence of large oral doses of ascorbic acid on the urinary excretion of calcium has been investigated. In the first experiment, daily doses of a total of 10 g of ascorbic acid were administered to healthy human subjects. Daily urinary samples of these subjects were collected before and during the treatment, and calcium contents of these samples were measured. Among the 22 subjects, 19 experienced no significant changes in urinary calcium levels during the ingestion of ascorbic acid, one subject experienced an increase, two had a decline. These changes in urinary calcium levels were relatively small and were within the changes from consuming normal diets. In the second experiment, urinary samples of 46 healthy subjects were collected during a period of 8 hours after the ingestion of 2 g of ascorbic acid (33 times the U.S. RDA). A significant increase in mean urinary calcium excretion from 48.2 +/- 25.1 mg to 58.3 +/- 28.0 mg in the 8-h time period was observed. Mean urinary volume and phosphorus were unchanged. Calcium levels of the initially low excretors were significantly elevated while the change in urinary calcium levels of the initially high excretors was not statistically significant following the administration of ascorbic acid. The results suggest that ascorbic acid has a short-term effect on the regulation of the absorption and metabolism of calcium in humans.

Adult↗

PubMed2002

Differences in the accumulation of ascorbic acid in normal, myeloperoxidase deficient and NADPH-oxidase deficient granulocytes.

Granulocytes contain large quantities of ascorbic acid (AA). The uptake mechanism is mainly restricted to the accumulation of the oxidized form, dehydroascorbate (DHA). We investigated the uptake of ascorbic acid and dehydroascorbate of normal, myeloperoxidase (MPO)-deficient, and NADPH-oxidase-deficient granulocytes. The accumulation of ascorbic acid was increased in all types of granulocytes after stimulation with phorbol-myristate-acetate, whereas the NADPH-oxidase-deficient cells showed a decreased uptake compared to normal and MPO-deficient cells. The intracellular concentration of ascorbic acid was further enhanced after incubation of granulocytes with DHA, most prominently in NADPH-oxidase-deficient granulocytes. MPO-deficient granulocytes are not able to produce HOCl after activation. The granulocytes of one individual with total MPO deficiency accumulated ascorbate in higher concentrations than did cells with partial MPO deficiency, indicating that HOCl is of minor importance for the oxidation of ascorbate. Since the ability of MPO-deficient cells to kill microorganisms is pronounced in contrast to NADPH-oxidase-deficient cells, effective mechanisms of compensating for the absence of HOCl must exist. We hypothesize that the enhanced uptake of ascorbic acid combined with an enhanced superoxide anion production may favor the generation of OH radicals via the Fenton reaction.

Antioxidants↗

PubMed1987

Effect of ascorbic acid on the consequences of acute alcohol consumption in humans.

This study examines the influence of ascorbic acid pretreatment on ethanol clearance, toxicity, and behavioral impairment after an acute dose of ethanol in humans. Ascorbic acid or a placebo was given to 20 healthy male subjects for 2 weeks before ethanol consumption. The dose of ethanol was 0.95 gm/kg body weight and was consumed during a 2 1/2-hour period. Thirty minutes after ethanol consumption, motor coordination and intellectual function were assessed by Goldberg's "Finger-Finger" and "Serial Sevens" tests. In addition, color discrimination was measured with the use of the Farnsworth-Munsell 100 Hue Color Test. Hourly blood samples were taken for 10 hours after ethanol consumption to measure serum triglyceride levels, blood lactate/pyruvate ratios, and serum enzymes. Blood ethanol clearance was also determined. Ethanol consumption elevated serum triglyceride levels and blood lactate/pyruvate ratios and impaired performance of the behavioral tests but did not alter serum enzyme levels. Ascorbic acid pretreatment resulted in significant enhancement in blood ethanol clearance and an increase in serum triglyceride levels after ethanol consumption in half of the subjects. Ascorbic acid pretreatment also resulted in improved motor coordination and color discrimination after ethanol consumption in half of the subjects. Ascorbic acid pretreatment did not influence elevated blood lactate/pyruvate ratios or impaired intellectual function.

Adult↗

PubMed1985

Enhancement of methyl mercury-induced lipid peroxidation by the addition of ascorbic acid.

Effects of mercuric chloride (HgCl2) and methylmercuric chloride (MMC) in the presence of ascorbic acid on lipid peroxidation in rabbit renal cortical mitochondria were studied. The addition of ascorbic acid showed no effect on HgCl2-induced lipid peroxidation, but ascorbic acid plus MMC were able to stimulate the lipid peroxidation markedly. This result suggests that in the presence of ascorbic acid MMC has a powerful stimulatory effect on the lipid peroxidation in mitochondria.

Animals↗

PubMed1996

Ascorbic acid may protect against human gastric cancer by scavenging mucosal oxygen radicals.

High dietary ascorbic acid intake appears to protect against gastric cancer. This may be due to its action as a scavenger of reactive radical species formed in the gastric mucosa, resulting in a reduced level of radical-mediated DNA damage. We have studied 82 patients, of whom 37 had Helicobacter pylori-associated gastritis, a condition which predisposes to gastric cancer. Using electron paramagnetic resonance (EPR) spectroscopy we have demonstrated, for the first time, that ascorbyl radicals are generated in human gastric mucosa, presumably as a result of scavenging of free radicals by ascorbic acid. Quantification of ascorbyl radicals demonstrates that there is a higher concentration in those patients with H.pylori gastritis compared with subjects with normal histology (P < 0.01). We also found gastric mucosal luminol-enhanced chemiluminescence and malondialdehyde concentrations (which are believed to be markers of radical generation and tissue damage) to be higher in patients with H.pylori gastritis compared with those with normal histology (P < 0.001 and P < 0.01 respectively). The observed concentrations of the ascorbyl radical correlate with the level of luminol-enhanced chemiluminescence (r = 0.41, P < 0.001), but not with malondialdehyde concentrations (r = 0.08, P = 0.47). Mucosal ascorbic acid and total vitamin C concentrations did not vary between histological groups, nor did they correlate with mucosal levels of the ascorbyl radical, chemiluminescence or malondialdehyde. These data suggest that ascorbic acid is acting as a scavenger of free radicals generated in human gastric mucosa. The experiments therefore provide direct supportive evidence for the hypothesis that ascorbic acid protects against gastric cancer by scavenging reactive radical species which would otherwise react with DNA, with resultant genetic damage.

Adult↗

PubMed1990

Uptake of ascorbic acid by freshly isolated cells and secretory granules from the intermediate lobe of ox hypophyses.

Mechanically isolated cells from the intermediate lobe of ox hypophyses contained 40.6 +/- 3.7 nmol mg-1 protein (mean +/- SE, n = 5) of ascorbic acid. They accumulated radioactivity time dependently, on incubation with L-[14C]ascorbic acid in ionic medium dominated by NaCl. No definite saturation of uptake occurred when mechanically isolated cells were incubated with increasing ascorbic acid concentrations up to 0.6 mM. But if such cells were purified on a Percoll gradient, a clear saturation of uptake could be observed. Acetylsalicylic acid reduced the uptake markedly. When cells loaded with L-[14C]ascorbic acid were homogenized and placed on a Percoll gradient, the radioactivity was recovered in several subcellular fractions. Decrease of the Na+ concentration or presence of ouabain in the medium did not cause noticeable changes in uptake by non-purified cells, whereas uptake by purified cells was clearly sodium-dependent. Phloridzin inhibited uptake. Secretory granules from pars intermedia contained 40.0 +/- 3.8 nmol mg-1 protein of ascorbic acid (mean +/- SE, n = 3) and could accumulate L-[14C]ascorbic acid rapidly in a KCl-dominated medium. The uptake was not saturable with ascorbic acid concentration and was not influenced by the presence of I mM ATP + I mM Mg2+ in the medium. The concentration of copper and iron in isolated cells was comparable to that in isolated neurohypophysial nerve terminals, whereas the concentration of zinc was considerably higher in the pars intermedia cells. The concentration of Cu, Zn, Fe and Co in secretory granules from pars intermedia was higher than in secretory granules from neurohypophyses.

Animals↗

PubMed2005

Flow-injection determination of ascorbic acid and cysteine simultaneously with spectrofluorometric detection.

A simple and sensitive spectrofluorometric method was developed for the simultaneous determination of ascorbic acid and cysteine by a flow-injection system. This method is based on the reduction of Tl(III) with ascorbic acid or cysteine in acidic media, producing fluorescence reagent, TlCl3(2-) (lambdaex = 227 nm, lambdaem = 419 nm). The injected sample solution was divided into two separate streams. The first stream was treated with Tl(III) at pH 3.0 and then passed through a 270 cm reaction coil to the flow cell of the spectrofluorometer, where the fluorescence intensity was measured. This signal is related to ascorbic acid and cysteine concentration. The second part of the injected sample solution was treated with Tl(III) in HCl solution and then passed through a 50 cm reaction coil to the flow cell and the fluorescence intensity was measured. This signal is related only to cysteine. Thus, the ascorbic acid content was determined directly by the difference according to the calibration curve. Ascorbic acid and cysteine can be determined in the range of 1 x 10(-6) to 5.0 x 10(-5) M, at a rate of 16 samples per hour. The limits of detection (S/N = 3) were 8 x 10(-7) M for ascorbic acid and 7 x 10(-7) M for cysteine. The influence of potential interfering substances was studied. The proposed method was successfully applied to the simultaneous determination of both analytes in real samples.

Ascorbic Acid↗

PubMed1992

Sex variation in ascorbic acid catabolism.

Male and female albino rats of same age and body weight were pair fed with laboratory stock diet and ascorbic acid, dehydroascorbic acid and diketogulonic acid were determined in the liver and urine, while in blood only ascorbic acid was estimated. Male rats had concentration higher of ascorbic acid in liver and urine as compared with females, while there were no significant variations in the contents of dehydroascorbic acid and diketogulonic acid. Hepatic and renal 2, 3-diketoaldonate decarboxylase, and hepatic dehydroascorbatase were also found to be significantly higher in male rats. Similar sex variations were also observed in ascorbic acid catabolism in guinea pigs without any differences in urinary ascorbic acid contents.

Animals↗

PubMed1994

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.

Adolescent↗

PubMed1998

Effect of alpha-tocopherol and ascorbic acid on bovine in vitro fertilization.

The aim of this work was to study the effect of alpha-tocopherol (vitamin E) and ascorbic acid on the in vitro fertilization process. Frozen bovine semen was prepared using extenders with and without addition of vitamin E. Samples were capacitated with heparin in the fertilization medium. In vitro matured oocytes were inseminated with spermatozoa frozen with and without vitamin E and, after thawing, fertilized in TALP medium (control) and in TALP medium with vitamin E (1 mg/ml), with ascorbic acid (5 mM) and with vitamin E plus ascorbic acid. Gametes were incubated in the respective fertilization medium for 48 h; those frozen without vitamin E yielded 75, 76, 69 and 49% of fertilized oocytes in the control, vitamin E, ascorbic acid and vitamin E plus ascorbic acid media, respectively. The last value was significantly different (P < 0.01). In bovine sperm frozen with vitamin E, fertilization rates were 74, 50, 47 and 34%, respectively for the 4 groups. Values observed for the different supplements were significantly different inter se (P < 0.01), except between the media with vitamin E and with ascorbic acid. These results indicate that preserved antioxidant capacity of vitamin E impairs the success of the in vitro fertilization process.

Animals↗

PubMed1999

Effect of direct compression excipients on the stability of ascorbic acid (vitamin c) tablets.

The effects of four directly compressible excipients such as Avicel, Dipac, Ditab and Emdex on the stability of ascorbic acid tablets were evaluated. Ascorbic acid tablets were formulated by the direct compressive method at constant temperature and pressure. In vitro tablet properties such as weight uniformity, hardness, friability, moisture content, disintegration time and dissolution rate were evaluated. The tablets were also subjected to temperature and moisture stresses in order to assess their stability. The results obtained indicated that moisture and temperature affect the stability of ascorbic acid tablets. All the tablet batches exhibited very short shelf lives in the presence of the stress conditions of temperature and moisture. None of the four excipients could be recommended for use in tableting ascorbic acid based on the shelf lives.

Ascorbic Acid↗

PubMedDate not supplied

Leucocyte and serum ascorbic acid levels in mothers and their newborn in semi-arid western India.

Leucocyte ascorbic acid (LAA) and serum ascorbic acid (SAA) have been estimated in 50 pregnant women, their newborn infants, and 14 non-pregnant women living in the semi-arid region of western India. LAA was significantly higher in the newborn as compared to their mothers, the mean values being 35.52 +/- 6.85 and 23.94 +/- 5.84 micrograms/10(8) cells, respectively (P less than 0.01). The sex and birth weight of the infant, however, did not influence its ascorbic acid status. Pregnant women had relatively lower SAA (0.81 +/- 0.22 mg/dl) and LAA (23.94 +/- 5.84 micrograms/10(8) cells) as compared to the matched non-pregnant group (1.01 +/- 0.26 mg/dl and 29.98 +/- 8.45 micrograms/10(8) cells). But despite the semi-arid, draught prone geographical region and the hemodilution which accompanies pregnancy, none of the mothers had a clearly subnormal vitamin C status.

Ascorbic Acid↗