Der Hyaluronsäuregehalt und die «Hyaluronidase»-Aktivität der Leukozyten

Summary The hyaluronic acid content of leucocytes from the peritoneum of rats shows a significant concentration when measured either turbidimetrically or oxydimetrically, the average value calculated for wet weight being 0.7–0.8%. The hyaluronic acid break down capacity of the leucocytes is not a specific enzyme action but can be attributed to their high ascorbic acid content. The phenomenon has no well defined pH or temperature optimum and can be inhibited by oxine and by semicarbazide.     

Effects of L-lysine administration on certain aspects of ascorbic acid metabolism in weanling rats

Summary L-lysine administration to male weanling rats at a dose of 110.4 mg (25% LD₅₀) per 100 g body weight per day for 15 days reduced the liver total ascorbic acid level. The biosynthesis as well as the degradation of L-ascorbic acid was diminished under these conditions. The fall in liver total ascorbic acid level after L-lysine administration was ascribed to its reduced synthesis.Acknowledgment. The authors are thankful to the Council of Scientific and Industrial Research, India, for providing Junior Research Fellowships to Miss J. Basu and Miss K. Sen Gupta.     

Protective effects of vitamin E and dithiothreitol against the hemolysis of rat and goat erythrocytes induced by Tween 20 with or without ascorbic acid and azide

Summary Exrtensive in vitro hemolysis of erythrocytes, induced in vitamie E-deficient rats by 0.001% Tween 20 with ascorbic acid and azide, or in goats by 2.5% Tween 20, could be counteracted by either the inclusion of vitamin E in the cells or by the in vitro addition of 0.25–0.4 mM dithiothreitol.     

Primitive actimoterigian fishes can synthesize ascorbic acid

Amphibians and reptiles evolved with the capacity to synthesize ascorbic acid. Some higher vertebrates, like bats, guinea pigs, primates, and humans have lost the microsomal enzyme gulonolactone oxidase, and in cases of ascorbic acid deficiency suffer from symptoms of scurvy. The question of whether the capacity to synthesize ascorbate is also present in lower vertebrates could throw light on the evolution of this pathway. In order to find out whether ascorbic acid synthesis took place in two primitive Actinopterigian fish, the paddlefish (Polydon spathula) and the white sturgeon (Acipenser transmontanus) were fed with a scorbutogenic diet or diet(s) supplemented with a graded level of ascorbic acid. We found no growth depression nor external symptoms of scurvy, which would be pronounced in modern bony fishes (Teleostei) under similar conditions. The tissue level of ascorbate in both these primitive species indicated that vitamin C in intestine and liver is not depleted when fed a scorbutogenic diet. Gulonolactone oxidase activity was found in the kineys of the Actinopterigian fishes. Thus, I question the accepted evolutionary pathway for ascorbic acid biosynthesis in lower vertebrates and suggest that the modern bony fishes,Teleostei, lost their ability to express the gulonolactone oxidase genes after they had separated during the Silurian from their common ancestor with the coelacanths (Latimeria) and Dipnoi.     

Noradrenergic control of ascorbic acid and glutathione concentrations in brown fat of cold-exposed rats

Summary Ascorbic acid and glutathione concentrations increase in brown fat of cold-exposed rats. This phenomenon can be reproduced by noradrenaline or isoproterenol administration, and thus seems to be under sympathetic control. Histological study shows ascorbic acid storage in brown adipocyte nuclei.     

Effect of cold exposure on electrophysiological properties of rat heart

Male rats exposed to the cold (4°C) for five or ten days exhibited modifications in their thyroid state, as documented by increases in serum thyroid hormone levels, to which differently graded modifications of heart weight/body weight ratio, heart rate, and resting metabolic rate were associated. The values of the above mentioned thyroid state indicators returned to those of the control when the animals, kept at cold for ten days, were re-exposed to room temperature (24°C) for an additional 10 days. The configuration of action potentials, recorded in vitro at 26°C from fibres of anterior papillary muscles, was different in control rats of different age and was affected by prolonged cold exposure. In fact, the action potential duration (APD) increased after ten days of cold exposure. In the re-exposed group the APD was not different from that of the controls. Such a pattern was not significantly modified when the stimulation frequency increased from 1 Hz to 5 Hz. The above results suggest that in cold exposure, as in experimental hyperthyroidism, thyroid hormone might exert a cardiac chronotropic effect by modifying heart electrophysiological properties. Thus thyroid hormone should play a basic role during the exposure to cold environment, stimulating the body metabolism and increasing heart rate as a response to the requirement for greater tissue perfusion.     

Noradrenergic control of ascorbic acid and glutathione concentrations in brown fat of cold-exposed rats

Ascorbic acid and glutathione concentrations increase in brown fat of cold-exposed rats. This phenomenon can be reproduced by noradrenaline or isoproterenol administration, and thus seems to be under sympathetic control. Histological study shows ascorbic acid storage in brown adipocyte nuclei.     

Evolutionary implications of ascorbic acid production in the Australian lungfish

Summary It is shown that the Australian lungfish (Neoceratodus forsteri) synthesizes ascorbic acid in its kidney, suggesting that ascorbic acid synthesis started before the origin of the tetrapods.Acknowledgments. We would like to thank Dr G.C. Grigg, University of Sydney, Mr R. B. Humphries, Dr P.A. Janssens and Dr C.H. Tyndale-Biscoe, Australian National University, and Dr. M. Griffiths and J.C. MacIlroy C.S.I.R.O., Division of Wildlife Research for supplying the tissue.     

Tissue ascorbic acid and a liver dehydroascorbatase in guinea-pigs.

The extraction, partial purification and assay of a dehydroascorbatase from guinea-pig liver is described. There was no evidence that changes in dehydroascorbatase activity could account for the modified tissue ascorbic acid concentrations associated with aging or with the ingestion of fluoride, flavonoids or anthocyanin material.     

Tissue ascorbic acid and a liver dehydroascorbatase in guinea-pigs

Summary The extraction, partial purification and assay of a dehydroascorbatase from guinea-pig liver is described. There was no evidence that changes in dehydroascorbatase activity could account for the modified tissue ascorbic acid concentrations associated with ageing or with the ingestion of fluoride, flavonoids or anthocyanin material.Supported by a Beechams Products grant.     

Einfluss der Temperatur auf den Vitamin-C-Gehalt während des Wachstums von englischem Spinat (Rumex patientia L.)

Summary Growth and ascorbic acid content of English spinach (Rumex patientia L.) were determined during a period of 7 weeks in the phytotron and also in the open field in relation to temperature. As compared with constant warm temperature, a low average temperature in the phytotron resulted in significantly increased plant weights and increased ascorbic acid contents. The results of the open field studies showed great deviations in plant weight and ascorbic acid content, due to metereological conditions. Generally, the content of ascorbic acid in spinach increased with the growth of the plants.     

Cinétique de l'inhibition de l'oxydation cuprique de l'acide ascorbique par certains complexants

Summary The authors studied the kinetics of the inhibition of the copper-catalysed oxydation of ascorbic acid by versene and some proteins. The versene-inhibition attains slowly the theoretical value, when added after the Cu⁺⁺ to ascorbic acid. Proteins inhibit non-competitively and completely, when added to the vitamine either after or before the copper. This result may be interpreted as indicating an interaction between protein and the complex (AH-Cu⁺⁺).

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Note N^o 2 sur l'oxydation cuprique de l'acide ascorbique. Note N^o 1, voir réf.³.     

Pentagastrine,histamine et acide ascorbique de la muqueuse gastrique chez le rat

Summary Pentagastrin and histamine, 2 potent gastric acid stimulants, lower ascorbic acid in the rat's gastric mucosa. They give the same result as nerve stimulation by desoxyglucose. Explanation of ascorbic acid function in gastric physiology needs further work.     

In vivo voltametric measurement of ascorbic acid and DOPAC in the striatum of the rat and guinea-pig

Differential pulse voltammetry was performed with electrochemically treated carbon fiber electrodes. By this technique, ascorbic acid and catechol compounds were resolved in vitro in two distinct peaks. Similar oxidation peaks were obtained in vivo from the striatum of Rats and Guinea-Pigs. From electrochemical and pharmacological observations it is suggested that they correspond to the oxidation of extracellular ascorbic acid and 3,4-dihydroxyphenyl acetic acid (DOPAC).     

Biosynthesis of ascorbic acid in chick embryos

Biosynthesis of ascorbic acid was found in the kidneys (mesonephros and metanephros) of the chick embryo as well as in the yolk sac membrane. The activity of L-gulonolactone oxidase in the yolk sac membrane suggested that it was the major source of ascorbic acid in the chick embryo.     

Wirkung der Adrenalektomie und Desoxycorticosteronbehandlung auf die Ascorbinämie und Ascorbinurie der Katze

Summary Two cats were adrenalectomized and kept healthy with daily injections of desoxycorticosterone acetate. The ascorbic acid concentration of blood and urine remained the same as in normal controls. When Dexoxy-corticosterone was omitted, a crisis ensued but the blood and urine concentration of ascorbic acid did not decrease.     

Effects of adrenal demedullation combined with chemical sympathectomy on cold-induced responses of endocrine pancreas in rats

Adrenal demedullation combined with chemical sympathectomy with 6-hydroxydopamine (ACS) lowered plasma glucagon and insulin levels in rats. Acute cold exposure increased plasma glucagon in both ACS and control rats, while it increased plasma insulin only in ACS rats. ACS rats responded to cold with a smaller increase in plasma glycerol and a more pronounced elevation of plasma free fatty acids.     

Die Wirkung der Askorbinsäure auf die Katalaseinduktion in Mikroorganismenkulturen

Summary Catalase activity ofStaphylococcus aureus increases the effect of ascorbic acid. Namely the ascorbic acid decreases the dissolved oxygen content of the medium, and low oxygen tension is the natural inducer of catalase synthesis.     

Ascorbic acid content of neotropical plant parts available to wild monkeys and bats

Summary The ascorbic acid content of foliage available to wild primates and bats in Panama (in transition between wet and dry seasons) was lower than that of temperate zone foliage but higher than that of most fruits and vegetables. Intakes of ascorbic acid (mg/kg b.wt/day) by wild primates and frugivorous bats in Panama are much greater than that of most human populations.     

Ascorbic acid content of neotropical plant parts available to wild monkeys and bats

The ascorbic acid content of foliage available to wild primates and bats in Panama (in transition between wet and dry seasons) was lower than that of temperate zone foliage but higher than that of most fruits and vegetables. Intakes of ascorbic acid (mg/kg b.wt/day) by wild primates and frugivorous bats in Panama are much greater than that of most human populations.