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  • Testosterone  (3)
  • (Notothenia coriiceps neglecta)  (1)
  • 1
    ISSN: 0014-5793
    Keywords: (Notothenia coriiceps neglecta) ; Amino acid sequence ; Antarctica fish ; Cold adaptation ; Hemoglobin
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 6 (1970), S. 133-142 
    ISSN: 1432-0827
    Keywords: Testosterone ; Dehydroepiandrosterone ; Glucosephosphate-dehydrogenase ; Glucose ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Les effets des androgènes (déhydroépiandrostérone et testostérone) sur le métabolisme des hydrates de carbone ont été étudiés en utilisant deux modèles expérimentaux. Le premier fait appel à la culturein vitro d'os embryonnaires d'oiseaux. Dans le deuxième modèle, on utilise des os non embryonnaires de mammifères, en cours d'ossification enchondralein vivo. Dans les deux cas, on note une augmentation de l'activité de la glucose-6-phosphate déhydrogénase et une oxydation différente de la glucose-1-14C et glucose-6-14C. Ces faits indiquent un changement dans le métabolisme du glucose allant vers la voie oxydative directe. En plus, le traitement provoque une hyperplasie de la couche hypertrophique dans l'épiphyse osseuse chez les souris prépubères.
    Abstract: Zusammenfassung Es wurden die Wirkungen von Androgenen (Dehydroepiandrosteron und Testosteron) auf den Kohlenhydratumsatz von Knochen mittels 2 experimenteller Modelle untersucht: einerseits anin vitro gezüchteten Bindegewebsknochen von Hühnerembryonen und andererseitsin vivo an nichtembryonalen Säugetierknochen mit endochondraler Ossifikation. In beiden Modellen läßt die Aktivitätszunahme der Glucose-6-phosphat-dehydrogenase und die unterschiedliche Oxydation von Glucose-1-14C und Glucose-6-14C eine Verschiebung des Glucosemetabolismus gegen den direkten oxydativen Abbau vermuten. Weiterhin erzeugt eine Behandlung mit diesen Hormonen eine Hyperplasie der hypertrophen Zellschicht an der Epiphysenplatte von vorpubertären Mäusen.
    Notes: Abstract An investigation on the effects of androgens (dehydroepiandrosterone and testosterone) on the carbohydrate metabolism of bone was carried out with two experimental models: avian embryonic membranous bone cultivatedin vitro, and mammal non-embryonic bone of endochondral ossificationin vivo. In both models, the increase in glucose-6-phosphate dehydrogenase activity and the differential oxidation of glucose-1-14C and glucose-6-14C suggest a shift in glucose metabolism toward the direct oxidative pathway. In addition, treatment with these hormones produces hyperplasia of the hypertrophic cell layer at the epiphyseal plate of prepubertal mice.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 2 (1968), S. 133-144 
    ISSN: 1432-0827
    Keywords: Dehydroepiandrosterone ; Testosterone ; Embryo ; Tissue culture ; Frontal bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Les os frontaux d'embryons de poulet, de 12 jours de développement, cultivés sur coagulum de plasma avec sulfate de déhydroépiandrostérone (DS) en concentration 1 mM, montrent hyperplasie du périoste et synthèse augmentée du matrice osseuse. Ces phénomenes ne son pas vus quand on emploie les os frontaux de 11 jours de développement. La testostérone produit les mêmes effets que le DS. Le deux steroïdes semblent agir directement sur l'os selon on peut le déduire des conditions expérimentales. L'activité de la phosphatase alcaline des frontaux d'embryons de poulet de 12 jours de développement est augmentée de manière significative quand les rudiments son cultivés dans un milieu qui contient DS ou testostérone. Dans ces deux cas: a) on peut révéler l'activation de l'enzyme par des expériences de cinétique enzymatique et b) les vélocités maximes apparantes ont une grande correlation avec le logarithme des doses employées. Quand les deux steroïdes son essayés en conditions semblables, les deux produisent la même augmentation de l'activité phosphatasique.
    Abstract: Zusammenfassung Wenn Stirnknochen von 12 Tage alten Hühnerembryonen in vitro auf koaguliertem Plasma mit Zusatz von 1 mM Dehydroepiandrosteronsulfat gezüchtet werden, so zeigen sie eine Hyperplasie des Periostes und eine erhöhte Synthese des Osteoidgewebes. Diese Erscheinung trifft nicht zu, ween 11 tägige Stirnknochen in gleicher Weise gezüchtet werden. Mit Testosteron werden gleiche Effekte wie mit Dehydroepiandrosteronsulfat erzielt. Aus den gewählten Versuchsverhältnissen kann abgeleitet werden, daß beide Steroide direkt auf den Knochen zu wirken scheinen. Die Aktivität der alkalischen Phosphatase im Stirnknochen des 12 Tage alten Hühnerembryos ist signifikant erhöht, wenn die Knochenansätze in einem Dehydroepiandrosteron oder Testosteron enthaltenden Medium gezüchtet werden. In beiden Fällen ergeben enzymkinetische Untersuchungen einerseits eine Aktivierung des Enzyms, andererseits eine gute Korrelation der erhaltenen scheinbaren Maximalgeschwindigkeiten mit dem Logarithmus der verwendeten Dosen. Bei gleichzeitiger Prüfung bewirkten beide Steroide gleichzeitig eine ähnliche Aktivitätszunahme der alkalischen Phosphatase.
    Notes: Abstract Chick embryo frontal bones at 12 days of development, cultivated in vitro on plasma clots with dehydroepiandrosterone sulfate in a concentration 1mM, exhibit periosteal hyperplasia and increased synthesis of osteoid tissue. These phenomena are not observed when 11-day frontals are cultivated in similar conditions. Testosterone produces the same effects as dehydroepiandrosterone sulfate. Both steroids seem to act directly on bone as can be inferred from the experimental conditions employed. The alkaline phosphatase activity of chick embryo frontal bones at 12 days of development is significantly increased when the rudiments are cultivated in a medium containing dehydro-epiandrosterone or testosterone. In both cases a) enzyme kinetics experiments revealed that there is activation of the enzyme and b) the apparent maximum velocities obtained are hihgly correlated with the logarithm of the doses employed. When assayed simultaneously, both steroids were found equally active in promoting the increase in alkaliue phosphatase activity.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 169 (1999), S. 303-310 
    ISSN: 1432-136X
    Keywords: Key words Corticosterone ; Testosterone ; Food-stress ; Nest-bound chicks
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In this study we examined hormonal responses of Black-legged Kittiwake (Rissatridactyla) chicks to experimental variations in energy content and nutritional quality (low or high lipid to protein ratio, LPR) of their food. Starting at the age of 10 days, chicks were fed either high or low LPR fish at 30, 50, 70 and 100% of ad libitum energy intake. After 20 days of treatment, chicks were exposed to a standardized acute handling and restraint stress protocol, where a baseline sample was taken immediately after taking a chick from the nest, and three additional blood samples were taken at intervals up to 50 min. Testosterone and corticosterone titres in plasma were measured via radioimmunoassay. We found that baseline testosterone levels were not significantly affected by the experimental treatments. Food-restricted chicks had elevated baseline and acute stress-induced levels of corticosterone compared to chicks fed ad libitum. An elevation of circulating levels of corticosterone in energetically stressed individuals was further magnified by low nutritional quality of food. Baseline and acute stress-induced corticosterone levels of chicks were negatively correlated with their fat reserves. We conclude that the physiological condition of Black-legged Kittiwake chicks can be assessed reliably by measuring circulating levels of corticosterone. We discuss short- and long-term effects of elevated corticosterone secretion in food-stressed nest-bound chicks.
    Type of Medium: Electronic Resource
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