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Showing papers on "Ascorbic acid published in 1980"


Journal ArticleDOI
28 Aug 1980-Nature
TL;DR: The DPV method used in conjunction with an electrochemical treatment of this electrode yields stable and reproducible peaks in which catecholamines and AA are resolved from each other, suggesting that the technique may be a useful means of following dopaminergic activity in vivo.
Abstract: Electroanalytical techniques for the in vivo measurement of neurotransmitters in brain tissue have been applied especially to the catecholamines, which are easily oxidizable. Measurements are, however, complicated by the presence of ascorbic acid (AA) in brain tissue. Lane et al. have been able to circumvent this problem, at least in part, by the application of differential pulse voltametry (DPV) to a surface-modified platinum electrode, obtaining distinct oxidation current peaks in recordings from the rat neostriatum which are attributed to AA and to dopamine (DA), respectively, but which are also unstable. We have recently described a new type of electrode, consisting of a pyrolytic carbon fibre 8 micrometers thick and 0.5 mm long. We now report that the DPV method used in conjunction with an electrochemical treatment of this electrode yields stable and reproducible peaks in which catecholamines and AA are resolved from each other. Moreover, pharmacological investigations suggest that the catecholamine peak measured in vivo in the rat neostriatum should be attributed to 3, 4-dihydroxyphenylacetic acid (DOPAC), suggesting that our technique may be a useful means of following dopaminergic activity in vivo.

396 citations



Journal ArticleDOI
TL;DR: An improved method was improved for the separate determination of L-ascorbic acid and L-dehydroascorbIC acid in blood plasma, using dithiothreitol, to determine the content of ascorbic acid.

319 citations


Journal ArticleDOI
TL;DR: During aging, the levels of vitamin C appear to decline in the human, guinea pig, and the mouse and synthetic antioxidants added to the diets of mice, have been noted to extend the lifespan and mean half-survivale times.
Abstract: The role of free radicals and lipid peroxidation is reviewed with regard to the aging process. Free radicals are produced during mitochondrial respiration, during the autooxidation of a variety of biological molecules and chemicals, during irradiation damage, and are found as environmental pollutants. Free radicals induce lipid peroxidation which results in membrane damage, increased disulfide/sulfhydryl ratios, and accumulation of aging pigments. Superoxide dismutase, glutathione peroxidase, vitamin E, vitamin C, and selenium are of importance with respect to free radical and lipid peroxide quenching. During aging, the levels of vitamin C appear to decline in the human, guinea pig, and the mouse. Synthetic antioxidants, added to the diets of mice, have been noted to extend the lifespan and mean half-survivale times.

315 citations


Journal ArticleDOI
TL;DR: The mode of breakdown of vitamin C can best be explained by a first-order reaction but a significant quadratic time effect has been determined by polynominal regression calculations.
Abstract: Variability in the vitamin C (ascorbic acid) contents of citrus fruit and their products is influenced by variety, cultural practice, maturity, climate, fresh fruit handling, processing factors, packaging, and storage conditions. Aerobic and anaerobic mechanisms are mainly responsible for the destruction of vitamin C in processed products. The mode of breakdown of vitamin C can best be explained by a first-order reaction but a significant quadratic time effect has been determined by polynominal regression calculations. Plots of log rate (loss of vitamin C) vs. 1/T for canned orange juice showed two distinct Arrhenius profiles, whereas canned grapefruit juice showed only one. Retention of vitamin C is greater in canned than bottled juices because of the reducing activity of the tinplate.

298 citations


Journal ArticleDOI
TL;DR: It is concluded that protein-calorie undernutrition is present in most hospitalized cancer patients but that it varies widely in degree between subjects and is often obscured at the bedside by residual obesity.

278 citations


Journal ArticleDOI
Stig Rehncrona1, David Smith1, Björn Åkesson1, Eva Westerberg1, Bo K. Siesjö1 
TL;DR: Measurements of changes in brain fatty acid and phospholipid composition may be a useful tool to establishment of whether peroxidative damage is important in vivo in situations with a critically reduced oxygen supply.
Abstract: The occurrence of peroxidative damage, as distinguished from anaerobic damage, to brain fatty acids and phospholipids was characterized in vitro. Fe2+ and ascorbic acid were used to stimulate peroxidation in cortical homogenates from rat brain incubated with or without oxygen. Lipid peroxidation was established in samples incubated with oxygen by increased diene conjugation, accumulation of thiobarbituric acid-reactive material (TBAR) and of lipid-soluble fluorescent products. No peroxidation occurred in samples incubated in the absence of oxygen (100% N2). Lipid peroxidation was characterized by a selective loss of arachidonic acid and docosahexaenoic acid and by degradation of ethanolamine phosphoglyceride, while choline phosphoglyceride did not change. During the course of peroxidation there were parallel increases in products of lipid peroxidation concomitant with the decrease in polyenoic fatty acids. The maximal changes in diene conjugation and TBAR occurred earlier than the maximal changes in fluorescent material and fatty acids. It is concluded that measurements of changes in brain fatty acid and phospholipid composition may be a useful tool to establishment of whether peroxidative damage is important in vivo in situations with a critically reduced oxygen supply. Estimation of lipid-soluble fluorescence in vivo may also be useful, since it is considered to reflect the accumulation of stable end products of peroxidation.

258 citations


Journal ArticleDOI
TL;DR: Results on human sera correlate well with those obtained by the previously described enzymatic method and the chemical colorimetric method.

245 citations


Journal Article
TL;DR: Observations provide strong evidence that the reactive intermediate formed in microsomes from acetarninophen and in solution from N-hydroxyacetaminophen is N-acetyl-p-benzoquinoneimine.
Abstract: Adding ascorbic acid to microsomal incubations containing acetaminophen inhibited covalent binding of the reactive metabolite. Adding ascorbic acid to incubations containing acetaminophen and cysteine markedly decreased acetaminophen-cysteine adduct formation. Ascorbic acid addition to aqueous incubations containing N-hydroxyacetaminophen and cysteine similarly inhibited the nonenzymatic formation of an acetaminophen-cysteine adduct. Therefore, the chemical reactions responsible for the nonenzymatic decomposition of N-hydroxyacetaminophen to yield acetaminophen-cysteine adducts were examined. In aqueous solutions above pH 7, N-hydroxyacetaminophen rapidly dehydrated to N-acetyl-p-benzoquinoneimine. In the absence of reducing compounds N-acetyl-p-benzoquinoneimine reacted with another molecule of N-hydroxyacetaminophen to give equal amounts of nitrosophenol and acetaminophen. The addition of cysteine or ascorbic acid slowed the decomposition of N-hydroxyacetaminophen and inhibited the formation of nitrosophenol. Cysteine effected these changes through decreasing the concentration of N-acetyl-p-benzoquinoneimine, primarily by reducing it to acetaminophen at low pH (5.5-7.0) or by conjugating with it to yield an acetaminophen-cysteine adduct at high pH (7.5-11.0). Ascorbic acid produced its effects only through reduction of the N-acetyl-p-benzoquinoneimine intermediate; thus acetaminophen was the only product. These observations provide strong evidence that the reactive intermediate formed in microsomes from acetarninophen and in solution from N-hydroxyacetaminophen is N-acetyl-p-benzoquinoneimine.

232 citations


Journal ArticleDOI
TL;DR: The hormone-supplemented medium may be generally useful for the establishment of human colon carcinoma cell lines and formed gland-like structures closely resembling the original tumor morphologically.
Abstract: A human colon carcinoma cell line, HC84S, was established in serum-supplemented medium from a colon tumor line T84 transplanted in nude mice. These cells also grew in a serum-free, synthetic medium supplement with insulin, glucagon, epidermal growth factor, transferrin, hydrocortisone, triiodothyronine, selenium, and ascorbic acid. HC84S cells grew 3 times faster in this medium than in serum-containing medium and formed gland-like structures closely resembling the original tumor morphologically. In serum-containing medium, the cells grew as a monolayer and did not form such structures. Primary cultures from transplantable human colon tumor lines maintained in nude mice and a primary tumor from a patient were established directly in this hormone-supplemented medium in collagen-treated plastic dishes without fibroblast overgrowth. The hormone-supplemented medium may be generally useful for the establishment of human colon carcinoma cell lines.

223 citations


Journal ArticleDOI
TL;DR: Ascorbic acid facilitates iron absorption by forming a chelate with ferric iron at acid pH that remains soluble at the alkaline pH of the duodenum.
Abstract: Food iron is absorbed by the intestinal mucosa from two separate pools of heme and nonheme iron. Heme iron, derived from hemoglobin and myoglobin, is well absorbed and relatively little affected by other foods eaten in the same meal. On the other hand, the absorption of nonheme iron, the major dietary pool, is greatly influenced by meal composition. Ascorbic acid is a powerful enhancer of nonheme iron absorption and can reverse the inhibiting effect of such substances as tea and calcium/phosphate. Its influence may be less pronounced in meals of high iron availability--those containing meat, fish, or poultry. The enhancement of iron absorption from vegetable meals is directly proportional to the quantity of ascorbic acid present. The absorption of soluble inorganic iron added to a meal increases in parallel with the absorption of nonheme iron, but ascorbic acid has a much smaller effect on insoluble iron compounds, such as ferric oxide or ferric hydroxide, which are common food contaminants. Ascorbic acid facilitates iron absorption by forming a chelate with ferric iron at acid pH that remains soluble at the alkaline pH of the duodenum. High cost and instability during food storage are the major obstacles to using ascorbic acid in programs designed to combat nutritional iron deficiency anemia.

Journal ArticleDOI
TL;DR: Pepino mosaic virus (PepMV), a previously undescribed virus, was found in fields of pepino in the Canete valley in coastal Peru and its properties are typical of the potexvirus group.
Abstract: SUMMARY Pepino mosaic virus (PepMV), a previously undescribed virus, was found in fields of pepino (Solanum muricatum) in the Canete valley in coastal Peru. PepMV was transmitted by inoculation of sap to 32 species from three families out of 47 species from nine families tested. It caused a yellow mosaic in young leaves of pepino and either a mild mosaic or symptomless infection in 12 wild potato species, five potato cultivars and potato clone USDA 41956 but S. stoloniferum and potato cultivars Merpata and Revolucion reacted with severe systemic necrotic symptoms. The virus was transmitted by plant contact but not by Myzus persicae. It was best propagated and assayed in Nicotiana glutinosa. Sap from infected N. glutinosa was infective after dilution to 10-1 but not 10-6, after 10 min at 65°C but not 70°C and after 3 months at 20°C. PepMV had filamentous particles with a normal length of 508 nm; the ends of some seemed damaged. Ultra-thin sections of infected leaves of N. glutinosa revealed many inclusions containing arrays of virus-like particles some of which were banded or whorled; small aggregates of virus-like particles were also common. The virus was purified by extracting sap from infected leaves in a solution containing 0·065 M disodium tetraborate, 0·435 M boric acid, 0·2% ascorbic acid and 0·2% sodium sulphite at pH 7·8, adding silver nitrate solution to the extract, and precipitating the virus with polyethylene glycol followed by two cycles of differential centrifugation. Particles of PepMV normally yielded two proteins with molecular weights of 26 600 and 23 200, but virus obtained from infective sap aged overnight yielded only the smaller protein suggesting that it was a product of degradation of the larger one. The virus is serologically related to two potexviruses, narcissus mosaic and cactus X and its properties are typical of the potexvirus group.


Journal ArticleDOI
TL;DR: In this paper, the electron transfer reactions between various copper(II) complexes and two-electron donors, such as ascorbic acid and 3,5-di-t-butylcatechol, were investigated.
Abstract: The electron transfer reactions between various copper(II) complexes and two-electron donors, such as ascorbic acid and 3,5-di-t-butylcatechol, were investigated Mononuclear copper(II) complexes with a distorted tetrahedral and a trigonal bipyramidal structure, and some binuclear complexes were readily reduced to copper(I) complexes by the two-electron donors, but not mononuclear planar copper(II) complexes The catalytic activities of these copper(II) complexes for the oxidation of 3,5-di-t-butylcatechol by O2 were studied in relation to the above reactions

Journal ArticleDOI
TL;DR: Administration of indomethacin caused complete resolution of a desmoid tumor after a partial response to radiation and in another patient, this drug caused an immediate response, then became ineffective.
Abstract: Administration of indomethacin caused complete resolution of a desmoid tumor after a partial response to radiation. In another patient, this drug caused an immediate response, then became ineffective. When large doses of ascorbic acid were given with indomethacin, slow resolution of the tumor began and has continued for 14 months. Treatment of a third case with indomethacin and ascorbic acid from the beginning produced shrinkage of the tumor which has continued to date.

Journal ArticleDOI
TL;DR: Results by the present method correlate well with those by the colorimetric method involving 2-(2-thiozolylazo)-p-cresol, and replicate analyses of standard solution and of two kinds of control sera demonstrated the following between-assay precision.
Abstract: We describe the enzymic determination of free fatty acids in serum with use of acyl-CoA synthetase (EC l.2.1.3), acyl-CoA oxidase (no EC no. assigned) and peroxidase (EC 1.11.1.7). The free fatty acids are activated by acyl-CoA synthetase in the presence of ATP and coenzyme A. The acyl-CoA formed is oxidized by acyl-CoA oxidase to enoyl-CoA with simultaneous production of hydrogen peroxide, which is oxidatively coupled with 4-amino-antipyrine and 2,4-dibromphenol in the presence of peroxidase to yield a product that absorbs maximally at 505 nm. Standard curves prepared with various kinds of fatty acids are linear to at least 2.0 mmol/L and are practically congruent. Ascorbic acid or bilirubin interferes slightly. Results by the present method correlate well with those by the colorimetric method involving 2-(2-thiozolylazo)-p-cresol (r = 0.98). Replicate analyses of standard solution and of two kinds of control sera demonstrated the following between-assay precision: mean absorbance 0.224 (SD 0.002), CV 0.85%; mean concentration, 326 (SD 7.3) and 1076 (SD 22.7) mumol/L, CV 2.24 and 2.11%, respectively.

Journal ArticleDOI
TL;DR: Saponification before solvent extraction more efficiently released natural alpha-tocopherol from the feedstuffs than extraction before saponification, and increases in alpha-ocopherol content of 0--144% were obtained for the range of feedstUFF examined.
Abstract: Methods were compared for alpha-tocopherol determination involving saponification in the preparation of feed extracts for high performance liquid chromatography. The effects of antioxidant and saponification times used were also examined. The data obtained showed that saponification before solvent extraction more efficiently released natural alpha-tocopherol from the feedstuffs than extraction before saponification. Increases in alpha-tocopherol content of 0--144% were obtained for the range of feedstuffs examined. Ascorbic acid and pyrogallol used as antioxidants gave similar results, and extraction efficiency was independent of the time of saponification within the range 5--40 min.

Journal ArticleDOI
TL;DR: The average coefficient of variance for procollagen synthesis between replicate cultures was found to be relatively small, and the optimization of the culture conditions for the control cells has created a reliable and reproducible basis for employing human skin fibroblasts to study collagen metabolism in acquired and inherited diseases.

Journal ArticleDOI
TL;DR: In this paper, dry yellow peas, lentils, and faba beans were germinated under laboratory conditions, and a marked increase in ascorbic acid of the legumes was observed during germination.
Abstract: Dry yellow peas, lentils, and faba beans were germinated under laboratory conditions. Periodic rinsing with water at 2-hr intervals was effective in controlling microbial growth. Marked increase in ascorbic acid of the legumes was observed during germination. Amino acid contents did not change appreciably after 4day germination. Wheat flour blends containing ungerminated and germinated legume flours at 5, 10, and 15% levels were used in baking studies. Addition of 15% legume flours to bread resulted in only small deleterious effects on loaf volume, crumb grain, and flavor. Germination adversely affected the baking properties of peas and lentils, but not faba beans. Blanching of the germinated peas further impaired its baking properties.

Journal ArticleDOI
TL;DR: It is suggested that ascorbic acid may play a role in the pathogenesis of atherosclerosis, and although not implicated as an etiological factor in coronary artery disease, it suggests that a closer look at its possible role inThe pathogenesis and progression of coronary arteries disease is warranted.

Journal ArticleDOI
TL;DR: The appearance of insoluble collagen in the extracellular matrices produced by cultured human fibroblasts and calf endothelial cells was completely dependent on the presence of ascorbic acid and had variable effects on the quantity of glycoprotein(s) present in the matrix.
Abstract: 1 The effects of various concentrations of ascorbic acid on the quality and quantity of the insoluble extracellular matrices produced by two strains of cultured rat smooth-muscle cells were studied 2 Ascorbic acid was necessary for the appearance of insoluble collagen in the extracellular matrix 3 Secretion of soluble collagen continued in the absence of ascorbic acid, but this soluble collagen was markedly underhydroxylated 4 The amount of insoluble collagen present in the matrix was directly related to the ascorbic acid concentration 5 The insoluble collagen that appeared in the matrix under conditions where ascorbic acid was limiting was no more than 7% underhydroxylated 6 In contrast, the amount of insoluble elastin produced was inversely proportional to the ascorbic acid concentration 7 The elastin produced in the absence of ascorbic acid had the expected amino acid composition, but hydroxyproline was absent 8 The hydroxyproline content of elastin was also directly dependent on the ascorbic acid concentration 9 Ascorbic acid had variable effects on the quantity of glycoprotein(s) present in the matrix 10 The appearance of insoluble collagen in the extracellular matrices produced by cultured human fibroblasts and calf endothelial cells was also completely dependent on the presence of ascorbic acid

Journal Article
TL;DR: Growth of leukemic cells in culture was suppressed by L-ascorbic acid in a substantial proportion of patients with acute nonlymphocytic leukemia and was not due to its oxidation-reduction potential or pH change.
Abstract: The suppressive effect of L-ascorbic acid on the growth of bone marrow cells from patients with acute nonlymphocytic leukemia was studied using a modified agar culture method featuring daily feeding to allow the growth of leukemic cell colonies. In seven of 28 patients (25%), the numbers of leukemic cell colonies grown in culture were reduced to 21% of control by the addition of L-ascorbic acid (0.3 mM) to the culture medium. Glutathione did not suppress leukemic cell colonies although it has a similar oxidation-reduction potential to that of L-ascorbic acid. The addition of L-ascorbic acid reduced the pH of the medium. However, a comparable reduction of pH by the addition of HCl did not suppress leukemic cell colonies. In simultaneous cultures for leukemic and normal marrow cells, the suppression of leukemic cell colony was noted with a concentration of L-ascorbic acid as low as 0.1 mM (a concentration achievable in vivo), but normal myeloid colonies were not suppressed until the concentration of L-ascorbic acid reached an extremely high level (1 mM). In conclusion, growth of leukemic cells in culture was suppressed by L-ascorbic acid in a substantial proportion of patients with acute nonlymphocytic leukemia. This suppression was a specific effect of L-ascorbic acid and was not due to its oxidation-reduction potential or pH change. Leukemic cells were selectively affected at an L-ascorbic acid concentration attainable in vivo while normal hemopoietic cells were not suppressed.

Journal ArticleDOI
TL;DR: Calcium, vitamin A, and thiamin were the dietary nutrients most likely to be deficient, especially with women, and nutrient supplements, taken by 27 subjects, were generally inappropriate and frequently excessive.
Abstract: The nutritional status of 100 elderly women and men was evaluated in terms of their dietary nutrient intakes and selected biochemical measurements. Calcium, vitamin A, and thiamin were the dietary nutrients most likely to be deficient, especially with women. Nutrient supplements, taken by 27 subjects, were generally inappropriate and frequently excessive. Forty-one percent of the group had low serum protein concentrations. Values for hematocrit, hemoglobin, serum iron and ascorbic acid, plasma vitamin A and carotene were in acceptable ranges for 90% of the subjects. Biochemical values were not significantly correlated with dietary nutrients except for hemoglobin with dietary iron and serum ascorbic acid with dietary ascorbic acid. In a subsample of 20 persons, both dietary and serum folate values were low. Twenty subjects who lived in a retirement community that provided one major meal daily consumed less food than those who were completely independent but had similar biochemical values.

Journal ArticleDOI
TL;DR: The results imply that the protective effect of barbiturates under such conditions is unrelated to inhibition of lipid peroxidation, and suggest that instead they may act by other mechanisms.
Abstract: The protective effect of barbiturates in cerebral ischemia has been proposed to be related to inhibition of lipid peroxidation. The present in-vitro study was undertaken to test the efficiencies of different barbiturates to inhibit peroxidative reactions in brain tissue, and to compare their effects with established free radical scavengers (chlorpromazine and promethazine). Cortical homogenates, prepared from decapitated rats, were incubated at 37 C with 5 per cent O2 (in N2) in the presence of ferrous sulfate (0.01 mM) and ascorbic acid (0.25 mM). During incubation there was extensive lipid peroxidation in the tissue, as evidenced by appreciable production of thiobarbituric acid-reactive material (TBAR), 1.2 μmol malondialdehyde g−1 cortex in one hour. Thiopental (1.0 mM) caused a 96 per cent inhibition of TBAR production, while other barbiturates (in the same concentrations) had only small (methohexital) or no (pentobarbital and phenobarbital) inhibitory effect. The inhibition of TBAR production by 1.0 mM thiopental was similar to that found with 1.0 mM chlorpromazine or 0.1 mM promethazine. The inhibitory effect of thiopental on lipid peroxidation was confirmed by analysis of fatty acids and phospholipids. Thiopental prevented the peroxidative degradation of polyenoic (20:4, 22:6) fatty acids and of ethanolamine phosphoglyceride that otherwise occurred during incubation. The marked differences between the tested barbiturates with respect to their abilities to inhibit lipid peroxidation in vitro are at variance with the fact that all of these barbiturates have been reported to protect the ischemic brain in various situations in vivo. The results imply that the protective effect of barbiturates under such conditions is unrelated to inhibition of lipid peroxidation, and suggest that instead they may act by other mechanisms.

Journal ArticleDOI
TL;DR: The use of radio frequency plasma discharges of neat vinylferrocene to chemically modify pyrolytic graphite electrode surfaces is discussed in this paper, where the results indicate that the surface composition varies as a function of placement of the substrate in the plasma reactor.

Journal ArticleDOI
TL;DR: The results indicate that the Euglena peroxidase belongs to a new type of peroxIDase to be designated as l -ascorbic acid per oxidase, and the inhibition of the enzyme by cyanide and azide as well as absorption spectra of the enzymes alone and in complex with hydrogen peroxide showed that it is a hemoprotein.

Journal ArticleDOI
TL;DR: The second major interference, that from copper, is eliminated by adding 1 g of thiosemicarbazide per liter, which at a low pH forms a stable, uncolored complex with copper without affecting the reaction of ferrozine with iron.
Abstract: Serum iron is released from transferrin and reduced at pH 1.7 by treating serum with a 10 g/L ascorbic acid solution in 0.1 mol/L HCl. When ferrozine is added to this reagent, it forms a complex with iron that is as intensely colored as at higher pH values, and under these conditions no turbidity is produced. The second major interference, that from copper, is eliminated by adding 1 g of thiosemicarbazide per liter, which at a low pH forms a stable, uncolored complex with copper without affecting the reaction of ferrozine with iron.

Journal ArticleDOI
01 Jan 1980-Genetics
TL;DR: At least six nuclear loci are responsible for the genetic control of malate dehydrogenase in coleoptiles of maize and inter- and intragenic heterodimers are formed between sub-units specified by the three loci governing the mitochondrial MDH isozymes.
Abstract: At least six nuclear loci are responsible for the genetic control of malate dehydrogznase (L-malate: NAD oxidoreductase; EC 1.1 .I .37; MDH) in coleoptiles of maize. Three independently segregating loci (Mdh1, Mdh2, Mdh3) govern the production of MDH isozymes resistant to inactivation by ascorbic acid and found largely or solely in the mitochondria. A rare recessive allele found at a fourth nuclear locus (mmm) causes increased electrophoretic mobility of the MDH isozymes governed by the Mdh1, Mdh2 and Mdh3 loci. -Two loci (Mdh4, Mdh5) govern MDH isozymes that are selectively in- activated by homogenization in an ascorbic acid solution and that appear to be nonmitochondrial (soluble). Mdh4 and Mdh5 segregate independently of each other and independently of Mdhl, Mdh2 and Mdh3. However, there is close linkage between the migration modifier and Mdh4.—Multiple alleles have been found for all of the Mdh loci except the migration modifier, and electrophoretically "null" or near "null" alleles (as expressed in standardized sections of maize coleoptile) have been found for all loci except Mdh4. Duplicate inheritance commonly occurs for Mdhl and Mdh2 and also for Mdh4 and Mdh5.—Inter- and intragenic heterodimers are formed between sub-units specified by the three loci governing the mitochondrial MDH isozymes. The same is true of the alleles and nonalleles at the two loci governing the soluble variants. No such heterodimers are formed by interactions between mitochondrial and soluble MDH isozymes.

Journal ArticleDOI
TL;DR: Analysis of 437 human blood samples has shown that when the plasma-reduced ascorbic acid level falls below 1 mg/100 ml, the whole blood histamine level increases exponentially as the ascor bicarbonate level decreases.
Abstract: Analysis of 437 human blood samples has shown that when the plasma-reduced ascorbic acid level falls below 1 mg/100 ml, the whole blood histamine level increases exponentially as the ascorbic acid level decreases. When the ascorbic acid level falls below 0.7 mg/100 ml, there is a highly significant increase in the blood histamine level. Oral administration of ascorbic acid (1 g daily for 3 days) to 11 selected volunteers resulted in a reduction of the blood histamine level in every instance.

Journal Article
TL;DR: 3-Hydroxyacetaminophen has been isolated and identified as a microsomal metabolite of acetaminophen and analysis of the metabolite by gas chromatography-mass spectrometry revealed that it had a molecular ion and fragmentation pattern identical to that of authentic 3-hydroxyacetamine.
Abstract: 3-Hydroxyacetaminophen has been isolated and identified as a microsomal metabolite of acetaminophen. Analysis of the metabolite by gas chromatography-mass spectrometry revealed that the metabolite had a molecular ion and fragmentation pattern identical to that of authentic 3-hydroxyacetaminophen. Glutathione and ascorbic acid blocked covalent binding of reactive metabolite(s) to protein but did not block the formation of 3-hydroxyacetaminophen. Moreover, epoxide hydrolase did not block covalent binding of the reactive metabolite(s) to protein. Thus, the reactive metabolite apparently is not an epoxide substrate of the hydrolase, nor are 3-hydroxyacetaminophen and the reactive metabolite(s) formed from a common intermediate.