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H E Sauberlich

Bio: H E Sauberlich is an academic researcher. The author has contributed to research in topics: Ascorbic acid & Whole blood. The author has an hindex of 3, co-authored 3 publications receiving 1802 citations.

Papers
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Book ChapterDOI
TL;DR: This chapter discusses selected methods for the determination of ascorbic acid in animal cells, tissues, and fluids and suggests that prompt stabilization is especially important in the case of plasma or serum.
Abstract: Publisher Summary This chapter discusses selected methods for the determination of ascorbic acid in animal cells, tissues, and fluids. Methods for determining ascorbic acid are numerous. In general, chemical analyses for the vitamin are divided into two groups; the determination of the reduced form and the determination of the oxidized form. The former group of analyses is usually based upon the oxidation–reduction properties of ascorbic acid. These are widely used as the fundamental reactions in the measurement of vitamin C. The latter group of analyses is usually based upon the oxidation of the ascorbic acid and the subsequent formation of a hydrazone or a fluorophore. Best results are obtained if samples, especially plasma, are quickly stabilized with either trichloroacetic acid or metaphosphoric acid and immediately analyzed. Prompt stabilization is especially important in the case of plasma or serum. The greater stability of ascorbic acid in acid solution is because of the decreased tendency for the hydrolysis of the lactone ring with decreasing pH.

1,843 citations

Journal Article
TL;DR: It is suggested that leukocyte ascorbic acid values best represent the vitamin C status of the female Rhesus monkeys, and there was a tendency for plasma ascorBic acid levels to be directly related to liver asCorbic Acid levels.
Abstract: Eight female monkeys (Macaca mulatta) were fed an ascorbic acid-free diet for 7 weeks, followed by repletion with a supplementation of 10 mg ascorbic acid per kg of body weight for 3 weeks. Once each week the ascorbic acid contents of blood components and liver samples, obtained by closed needle biopsy, were determined as the 2,4-dinitrophenylhydrazine derivative. In selected animals the size of the total body pool ascorbic acid was determined by isotope dilution after administration (i.v.) of 14C-ascorbic acid. At no time were the monkeys frankly scorbutic. Values for r2 were less than 0.10 between plasma, whole blood, and erythrocyte ascorbic acid contents compared with the total body pool of ascorbic acid. Leukocyte ascorbic acid content was positively related to the total body pool of ascorbic acid (P less than 0.001, r2 = 0.923). Values for r2 were less than 0.15 when whole blood and (erythrocyte) ascorbic acid content were each compared with liver ascorbic acid levels; however, there was a tendency for plasma ascorbic acid levels to be directly related to liver ascorbic acid levels (P less than 0.05, r2 = 0.477), when plasma ascorbic acid was greater than 0.1 micrograms/ml. The relationship between liver ascorbic acid and leukocyte ascorbic acid levels was statistically significant (P less than 0.01, r2 = 0.683). The high correlation of leukocyte ascorbic acid levels with liver ascorbic levels and with the total body pool of ascorbic acid suggests that leukocyte ascorbic acid values best represent the vitamin C status of the female Rhesus monkeys.

12 citations

Journal Article
TL;DR: Under conditions of the present experiment, no elevation of apparent whole blood or plasma ascorbic acid was produced by inclusion of high levels of erythorbic acid in the diet, and measurements made on blood did not vary in response to changing ascorBic acid levels.
Abstract: Eight male Cynomolgus monkeys were fed an ascorbic acid-free total liquid diet until plasma levels decreased from a mean of 1.1 mg/dl to 0.04 mg/dl at 8 weeks. They showed no visible signs of scurvy. The animals were then given a daily oral dose of 10 mg ascorbic acid/kg body weight for 4 weeks, when the experiment was ended. Four of the animals were given, in addition, 200 mg erythorbic acid/kg body weight orally each day. In all animals repletion was accomplished in two to three weeks using return to initial plasma ascorbic acid levels as the criterion. During deficiency, blood cellular elements were found to be more resistant to depletion than plasma. For erythrocytes, this may be explained at least partially by the observation that in vitro uptake of ascorbic acid tended to be related inversely to blood ascorbic acid levels. However, no such relationship was seen in leucocytes or platelets. Other measurements made on blood did not vary in response to changing ascorbic acid levels. These include serum cholesterol; erythrocyte, leucocyte, or platelet counts; leucocyte differential; hemoglobin concentration; and hematocrit. Urinary hydroxyproline/creatinine ratios were also unchanged. Erythorbic acid, a stereoisomer of ascorbic acid and a common food additive, has been cited as a possible interferent in the determination of whole blood or plasma ascorbic acid, since in the guinea pig it is absorbed from the gut and no commonly used ascorbic acid analysis can distinguish between the isomers. Under conditions of the present experiment, however, no elevation of apparent whole blood or plasma ascorbic acid was produced by inclusion of high levels of erythorbic acid in the diet. Animals given erythorbic acid in addition to ascorbic acid during repletion did not differ from those given ascorbic acid alone in any aspect mentioned above.

6 citations


Cited by
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Journal ArticleDOI
TL;DR: The data presented in this report strongly support the hypothesis that plant tissues also synthesize NO via the nonenzymatic reduction of apoplastic nitrite and may have possible significance for germinating grain and for plant roots.
Abstract: Nitric oxide (NO) is an important signaling molecule in animals and plants. In mammals, NO is produced from Arg by the enzyme NO synthase. In plants, NO synthesis from Arg using an NO synthase-type enzyme and from nitrite using nitrate reductase has been demonstrated previously. The data presented in this report strongly support the hypothesis that plant tissues also synthesize NO via the nonenzymatic reduction of apoplastic nitrite. As measured by mass spectrometry or an NO-reactive fluorescent probe, Hordeum vulgare (barley) aleurone layers produce NO rapidly when nitrite is added to the medium in which they are incubated. NO production requires an acid apoplast and is accompanied by a loss of nitrite from the medium. Phenolic compounds in the medium can increase the rate of NO production. The possible significance of apoplastic NO production for germinating grain and for plant roots is discussed.

535 citations

Journal ArticleDOI
TL;DR: The evidence for and the evidence against the presence of the enzyme dehydroascorbate reductase in animal cells is outlined in a balanced way in an attempt to make sense of this continuing controversy.

484 citations

Journal ArticleDOI
TL;DR: Results show that rutin exhibits antihyperglycaemic and antioxidant activity in streptozotocin-induced diabetic rats.
Abstract: Flavonoids are non-nutritive dietary components that are widely distributed in plants. The present study investigated the antihyperglycaemic and antioxidant effect of rutin, a polyphenolic flavonoid in normal and streptozotocin-induced diabetic Wistar rats. Diabetes as induced in rats by an intraperitoneal injection of streptozotocin. Rutin was orally administered to normal and diabetic rats for a period of 45 days. Fasting plasma glucose, glycosylated haemoglobin, thiobarbituric acid reactive substances and lipid hydroperoxides were significantly (P<0.05) increased, whereas insulin, C-peptide, total haemoglobin, protein levels, non-enzymic antioxidants (glutathione, vitamin C, vitamin E and ceruloplasmin) were decreased significantly (P<0.05) in diabetic rats. Oral administration of rutin to diabetic rats significantly (P<0.05) decreased fasting plasma glucose, glycosylated haemoglobin and increased insulin, C-peptide, haemoglobin and protein levels. Administration of rutin also decreased thiobarbituric acid reactive substances and lipid hydroperoxides and increased the non-enzymic antioxidants significantly (P<0.05). Treatment of normal rats with rutin did not significantly (P<0.05) alter any of the parameters studied. These results show that rutin exhibits antihyperglycaemic and antioxidant activity in streptozotocin-induced diabetic rats.

442 citations

Journal ArticleDOI
TL;DR: Either other compounds present in plasma are likely to exert antioxidant action, or a marked synergistic action between antioxidants should be postulated to exist, as the latter hypothesis is supported by the finding that the simultaneous inactivation of ascorbate and thiol groups produces a loss in antioxidant capacity of plasma greater than the sum of the decreases produced by the separate in activation of each of the two compounds.

441 citations

Journal ArticleDOI
TL;DR: Measurements of the quantum efficiencies of photosynthetic electron transport through photosystem II (phiPSII) and CO2 assimilation (phiCO2) were made simultaneously on leaves of maize crops in the United Kingdom during the early growing season, when chilling conditions were experienced, supporting the hypothesis that the relative flux of photosynthesis reducing equivalents to O2 via the Mehler reaction is higher when leaves develop under chilling conditions.
Abstract: Measurements of the quantum efficiencies of photosynthetic electron transport through photosystem II (φPSII) and CO2 assimilation (φCO2) were made simultaneously on leaves of maize (Zea mays) crops in the United Kingdom during the early growing season, when chilling conditions were experienced. The activities of a range of enzymes involved with scavenging active O2 species and the levels of key antioxidants were also measured. When leaves were exposed to low temperatures during development, the ratio of φPSII/φCO2 was elevated, indicating the operation of an alternative sink to CO2 for photosynthetic reducing equivalents. The activities of ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, glutathione reductase, and superoxide dismutase and the levels of ascorbate and α-tocopherol were also elevated during chilling periods. This supports the hypothesis that the relative flux of photosynthetic reducing equivalents to O2 via the Mehler reaction is higher when leaves develop under chilling conditions. Lipoxygenase activity and lipid peroxidation were also increased during low temperatures, suggesting that lipoxygenase-mediated peroxidation of membrane lipids contributes to the oxidative damage occurring in chill-stressed leaves.

423 citations