Aufhebung der Thermothyrin-A-Sekretion der Schilddrüse durch Fütterung mit Methylthiouracil

Summary G. Mansfeld demonstrated that in the serum of overheated animals a substance (thermothyrine A) is present which, injected into normal animals, decreases O₂-consumption. Serum of thyroidectomized animals has no effect.Dogs and rabbits were treated daily with 0.10 g per kg methylthiouracil during 4 weeks, and were than subjected for 5 hours to a temperature of 34–35° C which raised their body temperature by 0.5–1.5° C. 2.5 cm³ of serum obtained at the end of the 5 hours period failed to reduce O₂-consumption of normal rats, while sera of untreated dogs and rabbits produced after similar exposure to high temperature a fall of O₂-consumption by 14–48%. It is therefore evident that methylthiouracil not only inhibits the formation of thyroxine but of thermothyrine A as well.The fact that thermothyrine A contains no iodine proves conclusively that the action of thiouracil compounds cannot be exclusively an inhibition of iodinization.     

Energy metabolism,respiration frequency and O2-consumption per breathing act in 11 different sunbird species during day and night

Summary The mean metabolic rates of 11 sunbird species are in the expected range based on data from other birds. Nevertheless the difference between day and night levels is greater (58–69%) than normal. Breathing frequencies among these birds correspond more closely to the (higher) levels found in empirical data for mammals. O₂-consumption per breathing act remains nearly constant during day and night indicating that the diurnal cycle of O₂-consumption is regulated mainly by modulation of breathing frequencies, which correlate directly with gaseous metabolism.     

A quick and modified Winkler-method for measuring O2-concumption of aquatic animals

Summary A modified procedure for measuring O₂-consumption, based on Winkler-method, is described. Instead of KI and HCl (or H₂SO₄) triphenylmethane-dye leukoberbelinblue I and citric acid are used.Acknowledgment. Md. B. expresses his gratitude to DAAD (German Academic Exchange Service, Bonn) for awarding him a post-doctoral fellowship, during the tenure of which this investigation was carried out.     

Die α-Glycerophosphat-Oxydation des Heuschreckenbrustmuskels (Locusta migratoria)

Summary The conditions were studied for the glycerophosphate oxidation by homogenate from locust flight muscle, and the O₂-consumption was measured. Maximal oxidation rates were found with 0.087m glycerophosphate, 8 × 10^–6 m cytochromec, 7 × 10^–6 m DPN and pH 7.5. The production of dihydroxyacetone phosphate is followed by further oxidation steps, as could be shown by estimation of the different fractions of acid-soluble phosphate. Comparative studies were made on different insects and vertebrates. The rate of succinate oxidation by insect muscle was found to be ten times higher than that of vertebrate muscle. The relation of glycerophosphate oxidation to succinate oxidation is quite different in insects and vertebrates, but no difference could be detected between the two types of muscle metabolism of insects: the carbohydrate and the fatutilizing type.

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Mit Unterstützung der Deutschen Forschungsgemeinschaft.     

Effect of sodium chloride on the respiratory function of Staphylococcus aureus.

Sodium chloride at concentrations below 0.5 M, enhanced the respiratory activity (O2-consumption) of Staphylococcus aureus under endogenous and sugar-supported conditions, but did not overcome the inhibitory action of sodium azide. Several sugars, including the glucose analogue alpha-methylglucoside, and their metabolites enhanced bacterial O2-consumption, but acetylmethylcarbinol was ineffective.     

Avilamycin

Summary A strain ofStreptomyces viridochromogenes produced a new crystalline antibiotic, Avilamycin, related to but not identical with Curamycin and Exfoliatin. Avilamycin, C₆₃H₉₄O₃₅Cl₂, gave on solvolytic degradation the following products: dichloroisoeverninic acid, 2-deoxy-d-rhamnose, 2,6-di-O-methylmannose, 4-O-methylfucose,l-lyxose and 3,5-diacetoxy--caprolactone.     

Oxygen equilibrium ofPriapulus hemerythrin

Summary The hemerythrin-containing coelomic fluid ofPriapulus caudatus shows a relatively low O₂ affinity (half-saturation O₂ tension P₅₀=8 mm at 10 °C) and a low O₂ capacity (near 1 vol.%). O₂ affinity is independent of pH but shows a large temperature sensitivity. A major role as a continuous O₂ transporter seems to be excluded.Acknowledgments. A major part of this work was carried out at the Kristineberg Marine Laboratory, Fiskebäckskil (Sweden) and in the Zoophysiology Department, Aarhus Universitet (Denmark).     

Interaction du 2,4-dichlorophénol et de l'eau oxygénée dans la destruction enzymatique de l'acideβ-indolylacétique

Summary DCP increases IAA destruction by bothLens andPhaseolus root breis. H₂O₂ inhibits catabolism byLens extracts but activates it whenPhaseolus is used, mainly when roots are cultivated in the dark and contain inhibitors of IAA destruction. DCP 1·10^–3 M and H₂O₂ 1·10^–4 or 1·10^–3 volume forLens and DCP 1·10^–4 M and H₂O₂ 1·10^–3 volume forPhaseolus nullify auxin catabolism.     

Über Struktur und Aktivität der den H2O2-Zerfall katalysierenden Cu2+-Komplexe. — VI. Differenzierung von nativer RNS und nativer DNS bzw. denaturierter DNS auf Grund der katalytischen Eigenschaften

Summary The catalysis of H₂O₂ decomposition by Cu²⁺-complexes of RNA and DNA has been investigated. It is shown that both complexes decompose H₂O₂, but only the Cu²⁺-RNA-system shows peroxidative activity too, e.g. only in this case the nucleotide bases are degraded. Thermal denaturation of DNA also leads to a Cu²⁺-complex with peroxidative activity, the latter being dependent on the degree of denaturation.

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V. Mitteilung:S. Petri, H. Sigel undH. Erlenmeyer, Helv. chim. Acta49, 1778 (1966).

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12. Mitteilung überMetallionen und H ₂ O ₂; 11. Mitteilung:H. Ch. Curtius, P. Anders, R. Zell, H. Sigel undH. Erlenmeyer, Helv. chim. Acta49, 2256 (1966).     

Ginkgo biloba extract inhibits oxygen species production generated by phorbol myristate acetate stimulated human leukocytes

Summary A Ginkgo biloba extract (Gbe) containing flavonoids, among other compounds, was tested for the release of activated oxygen species ( , H₂O₂, OH^.) during the stimulation of human neutrophils (PMNs) by a soluble agonist. The extract slows down O₂-consumption (respiratory burst) of stimulated cells by its inhibitory action on NADPH-oxidase, the enzyme responsible for the reduction of O₂ to . Consequently, superoxide anion ( ) and hydrogen peroxide (H₂O₂) production is significantly decreased when the PMNs stimulation is done in the presence of the extract at concentrations of 500, 250 and 125 g/ml. Moreover, the hydroxyl radical generation (OH^.) is very much decreased at concentrations as low as 15.6 g Gbe/ml, which indicates that the extract also has free radical scavenging activity. Gbe is able at least to reduce very severel the activity of myeloperoxidase contained in neutrophils. This enzyme, secreted into the intra and extracellular medium, catalyzes the oxidation of chloride (Cl^–) by H₂O₂ to yield strong oxidants (HOCl, chloramines) which are implicated in inflammatory processes     

Respiratory burst in peritoneal exudate cells in response to a modified tuftsin

Intraperitoneal administration of tuftsin-M [Thr–Lys–Pro–Arg–NH–(CH₂)₂–NH–CO–C₁₅H₃₁] to Balb/C mice has been shown to induce a respiratory burst in the peritoneal exudate cells. The macrophages exhibited enhanced levels of O₂ ^–, H₂O₂, NADPH oxidase and myeloperoxidase, but the activities of superoxide dismutase, catalase and glutathione peroxidase remained virtually unchanged. The magnitude of the oxidative burst depended directly on the dose of tuftsin-M; higher activity was observed at higher doses of the peptide. Tuftsin-M enhanced the generation of both O ₂ ^– and H₂O₂ under in vitro conditions, as did phorbol myristate acetate. These results suggest that tuftsin-M could enhance non-specific defence against infections by activating the macrophages.     

Oxidative stress triggers neuronal caspase-independent death: Endonuclease G involvement in programmed cell death-type III

To characterize neuronal death, primary cortical neurons (C57/Black 6 J mice) were exposed to hydrogen peroxide (H₂O₂) and staurosporine. Both caused cell shrinkage, nuclear condensation, DNA fragmentation and loss of plasma membrane integrity. Neither treatment induced caspase-7 activity, but caspase-3 was activated by staurosporine but not H₂O₂. Each treatment caused redistribution from mitochondria of both endonuclease G (Endo G) and cytochrome c. Neurons knocked down for Endo G expression using siRNA showed reduction in both nuclear condensation and DNA fragmentation after treatment with H₂O₂, but not staurosporine. Endo G suppression protected cells against H₂O₂-induced cell death, while staurosporine-induced death was merely delayed. We conclude that staurosporine induces apoptosis in these neurons, but severe oxidative stress leads to Endo G-dependent death, in the absence of caspase activation (programmed cell death-type III). Therefore, oxidative stress triggers in neurons a form of necrosis that is a systematic cellular response subject to molecular regulation. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

The superoxide-generating NADPH oxidase: structural aspects and activation mechanism

Flavocytochrome b ₅₅₈ is the catalytic core of the respiratory-burst oxidase, an enzyme complex that catalyzes the NADPH-dependent reduction of O₂ into the superoxide anion O₂ ^- in phagocytic cells. Flavocytochrome b ₅₅₈ is anchored in the plasma membrane. It is a heterodimer that consists of a large glycoprotein gp91phox (phox for phagocyte oxidase) (β subunit) and a small protein p22phox (α subunit). The other components of the respiratory-burst oxidase are water-soluble proteins of cytosolic origin, namely p67phox, p47phox, p40phox and Rac. Upon cell stimulation, they assemble with the membrane-bound flavocytochrome b ₅₅₈ which becomes activated and generates O₂ ^-. A defect in any of the genes encoding gp91phox, p22phox, p67phox or p47phox results in chronic granulomatous disease, a genetic disorder characterized by severe and recurrent infections, illustrating the role of O₂ ^- and the derived metabolites H₂O₂ and HOCl in host defense against invading microorganisms. The electron carriers, FAD and hemes b, and the binding site for NADPH are confined to the gp91phox subunit of flavocytochrome b ₅₅₈ . The p22phox subunit serves as a docking site for the cytosolic phox proteins. This review provides an overview of current knowledge on the structural organization of the O₂ ^--generating flavocytochrome b ₅₅₈ , its kinetics, its mechanism of activation and the regulation of its biosynthesis. Homologues of gp91phox, called Nox and Duox, are present in a large variety of non-phagocytic cells. They exhibit modest O₂ ^--generating oxidase activity, and some act as proton channels. Their role in various aspects of signal transduction is currently under investigation and is briefly discussed. Received 28 May 2002; received after revision 20 June 2002; accepted 24 June 2002     

Der Sauerstoffumsatz der Leber von Ratten während der Höhenakklimatisation

Summary The O₂-consumption of liver tissue of male rats of different ages during the first 10 days at an altitude of 3540 m was significantly decreased on the 5th and 7th day. The deviation from the controls at ground level was – 19% in 40-day-old and – 30% in 11-month-old male rats.

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Auslandsstipendiat der Schweizerischen Regierung (1963–64). Für die Überlassung eines Laboratoriums und der Apparate möchte ich Herrn Prof.A. v. Muralt auch an dieser Stelle danken.

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Die Arbeit wurde unterstützt von der Max-Planck-Gesellschaft zur Förderung der Wissenschaften, Deutschland. Ein Teil der Versuchstiere wurde uns freundlicherweise von der Hoffmann-La Roche AG, Basel, durch Herrn Dr.Loosli, Füllinsdorf (BL) zur Verfügung gestellt.     

Hydrogen peroxide protects tobacco from oxidative stress by inducing a set of antioxidant enzymes

Tolerance against oxidative stress generated by high light intensities or the catalase inhibitor aminotriazole (AT) was induced in intact tobacco plants by spraying them with hydrogen peroxide (H₂O₂). Stress tolerance was concomitant with an enhanced antioxidant status as reflected by higher activity and/or protein levels of catalase, ascorbate peroxidase, guaiacol peroxidases, and glutathione peroxidase, as well as an increased glutathione pool. The induced stress tolerance was dependent on the dose of H₂O₂ applied. Moderate doses of H₂O₂ enhanced the antioxidant status and induced stress tolerance, while higher concentrations caused oxidative stress and symptoms resembling a hypersensitive response. In stress-tolerant plants, induction of catalase was 1.5-fold, that of ascorbate peroxidase and glutathione peroxidase was 2-fold, and that of guaiacol peroxidases was approximately 3-fold. Stress resistance was monitored by measuring levels of malondialdehyde, an indicator of lipid peroxidation. The levels of malondialdehyde in all H₂O₂-treated plants exposed to subsequent high light or AT stress were similar to those of unstressed plants, whereas lipid peroxidation in H₂O₂-untreated plants stressed with either high light or AT was 1.5- or 2-fold higher, respectively. Although all stress factors caused increases in the levels of reduced glutathione, its levels were much higher in all H₂O₂-pretreated plants. Moreover, significant accumulation of oxidized glutathione was observed only in plants that were not pretreated with H₂O₂. Extending the AT stress period from 1 to 7 days resulted in death of tobacco plants that were not pretreated with H₂O₂, while all H₂O₂-pretreated plants remained little affected by the prolonged treatment. Thus, activation of the plant antioxidant system by H₂O₂ plays an important role in the induced tolerance against oxidative stress. Received 11 December 2001; received after revision 25 January 2002; accepted 4 February 2002     

The H2O2-production by polymorphonuclear leucocytes during phagocytosis

Riassunto Si può dimostrare un accumulo di H₂O₂ in leucociti polinucleati di essudato di cavia o di sangue umano durante la fagocitosi in presenza di KCN 2 mM. La produzione di H₂O₂ e l'attività della perossidasi si considerano importanti per l'azione battericida.     

Influence of oxygen concentration on development ofDrosophila melanogaster

Summary 1st, 2nd, and early 3rd instarDrosophila larvae are extremely sensitive to 100% O₂ or 75% O₂/25% N₂ (at atmospheric pressure) whereas eggs, late 3rd instar larvae, and pupae are relatively insensitive under our exposure conditions. Eclosing flies exposed to an O₂ enriched environment consistently possessed 2 eye abnormalities: dark eye color and altered eye shape.Supported by NSF-URP grant SP1782684 and a Summer Faculty Fellowship to Harry Nickla.     

Superoxide dismutase activity during the plasmodial life cycle ofPhysarum polycephalum

Summary Superoxide dismutase activity was slow throughout the cell cycle of surface cultures ofPhysarum polycephalum. This activity increased markedly when the organism was induced to spherulate. Glutathione (GSH) and hydrogen peroxide (H₂O₂) concentrations changed very little during the cell cycle. During spherulation GSH decreased; H₂O₂ and the cyanide-resistant respiration of plasmodial homogenates increased.     

Induction of the formation of a coli-bacterio-phage and colicin by hydroperoxide

Zusammenfassung Die Arbeit gibt die Resultate der Induktion der Lysogenie und der Colicinogenie im selben StammeE. coli (L II-18) mit Wasserstoffperoxid an. Der Phagentiter wurde 35mal, der Colicintiter 7mal erhöht. Die optimale Konzentration des H₂O₂ für Phagenbildung warM/500, die für ColicinbildungM/2000. Im Vergleich mit der Induktion desselben Stammes mit UV-Licht ist die Wirkung des H₂O₂ verhältnismässig schwach.     

Oxidative stress in the moderately halophilic bacteriumDeleya halophila: Effect of NaCl concentration

The sensitivity ofDeleya halophila to oxidative stress caused by hydrogen peroxide (H₂O₂) was found to vary, depending on the NaCl concentration of the growth medium. Pretreatment of the bacteria at a low concentration of H₂O₂ (50 M) protected the cells against the lethal effects of higher levels (1–2 mM) of H₂O₂. Exposure ofD. halophila cells to 50 M H₂O₂ resulted in the induction of several proteins (hydrogen peroxide-inducible proteins, hips). However, the kinetics of induction, the extent of induction and the number of hips appear to be influenced by the salt concentration of the growth medium. Five of the hips exhibited apparent molecular masses identical to those of five heat shock proteins (hsps).