Activation of the carcinogen N-hydroxy-2-acetylaminofluorene by rat mammary peroxidase

Summary A peroxidase preparation from rat mammary gland parenchymal cells, a target tissue of arylamine carcinogens, was shown to activate the carcinogen N-hydroxy-2-acetylaminofluorene via a nitroxyl free radical intermediate to the more active carcinogens nitrosofluorene and N-acetoxy-2-acetylaminofluorene. Hydrogen peroxide, cumene hydroperoxide, and linoleic acid hydroperoxide were effective as substrates. The antioxidants ascorbate, propyl gallate and reduced glutathione prevented the free radical activation route.     

Mechanism of reaction of carcinogen N-acetoxy-2-acetylaminofluorene with DNA

Summary Scavenging studies are supporting the notion that triplet radical cations are formed during the binding of the carcinogen N-acetoxy-2-acetylamino-fluorene to native DNA in vitro.This work was supported by Grant No.3305.78 of the Swiss National Science Foundation and by a grant from The Roche Research Foundation.     

Suppression of carcinogen-induced rat mammary tumor formation by Actinomycin D

Zusammenfassung Sprague-Dawley-Ratten, die eine kombinierte Belastung mit 7,12-Dimethylbenz()anthrazen und Aktinomyzin D überleben, weisen eine drastisch erniedrigte tastbare Tumorinzidenz auf. Kontrolltiere erhielten nur das Karzinogen.     

Activation of the pituitary-adrenal axis by nipple suction in the lactating rat]

The response of the pituitary-adrenal axis to suckling in lactating Rats is dependent on two factors: 1. a psychic factor, which is identical by its effects to the psychological stress of the strange environment (transitory increase of plasma corticosterone and no significant modification of the content of ACTH in the two lobes of the pituitary); 2. a specific factor namely the stimulation of the nipples, which is distinguishable from the psychic factor by a longer release of corticosterone by the adrenals and a durable and significant decrease of the content of ACTH in the pars distalis.     

Inactivation of tissue-specific inhibitors by a carcinogen (diethylnitrosamine)

Zusammenfassung Der Einbau von Thymidin in Leberexplantate wird durch lösliche Leberproteine gehemmt. Diese Hemmung ist aufgehoben, wenn die Proteine aus Lebern karzinogenbehandelter Tiere präpariert wurden. Dieser Effekt ist organspezifisch.     

Folic acid degradation by the peroxidase fromCicer arietinum

Résumé La peroxidase des plantules deCicer arietinum catalyse la transformation de l'acide folique dans 2-amino-4-hydroxy-6-formyl-pteridine et l'acidep-amino-benzoylglutamique. C'est peut-être le mécanisme responsable de la diminution de l'acide folique observée pendant la germination.     

Formation of histamine in transplants from a rat mammary carcinoma

Zusammenfassung Tumorgewebe von Ratten mit subcutan transplantiertem Walker-Milchdrüsencarcinom 256 produzierte¹⁴C-Histamin mit beträchtlicher Geschwindigkeit bei Inkubation des Krebsgewebes mit¹⁴C-Histidin. Zusatz von Pyridoxal-5-phosphat aktivierte die Histidindecarboxylase des Krebsgewebes. In normalem Milchdrüsengewebe lag die Histaminbildung ausserhalb des Messbereichs. Der Histamingehalt des Krebsgewebes war sehr niedrig und Mastzellen wurden keine gefunden. Der Histaminmetabolismus des Carcinoms 256 ist demjenigen im Rattenembryo und im Granulationsgewebe heilender Hautwunden ähnlich.     

Development of thyroid peroxidase activity during the early stage of iodine deficiency in the hypophysectomized rat]

The iodide-peroxidase activity of the thyroid gland remains, in hypophysectomized Rats maintained on a low iodine diet, below normal value. This result suggests that the early increase of peroxidase activity observed in control Rats maintained on a low iodine diet is TSH dependent.     

Properties of gamma-glutamyltranspeptidase, and glutathione levels in rat mammary gland

gamma-Glutamyltranspeptidase activity and glutathione levels were studied in rat mammary gland during the lactogenic cycle; both increased during mid-lactation. The enzyme's specific activity with several amino acids showed that glutamine and methionine were the best substrates. Maleate decreased the transpeptidation reaction and increased the hydrolytic activity. These results suggest that gamma-glutamyltranspeptidase from the mammary gland is similar to the enzyme described in other tissues in relation to these properties and the physiological role proposed in amino acids transport.     

Activation by S-adenosylhomocysteine of norepinephrine and serotonin in vitro uptake in synaptosomal preparations from rat brain

Summary S-Adenosylhomocysteine (10^–7–10^–5 M) activated norepinephrine (NE) and serotonin (5HT) in vitro uptake in synaptosomal preparations from rat brain, but did not affect dopamine (DA) uptake. When administered to rats (7 mg/kg i.p.), it had the same effect on in vitro NE and 5HT uptake. It did not affect NE and 5HT release.Work achieved within the frame of the research contract institut Mérieux., Institut National des Sciences Appliquées.     

Activation of complement by trypanosomes

Summary Factors exhibiting anti-complementary activity released from trypanosomes after incubation at 20°C were described. The active material was shown to consume the first component of bovine complement. While the anticomplementary factor(s) from T. lewisi could activate bovine, human and guinea pig complement, the factor(s) from T. congolense was observed to activate bovine complement, but not guinea pig and only slightly human complement. The roles of complement activating factor(s) of trypanosomes in the pathology of the disease are discussed.This project is supported by National Research Council of Canada grant A 0068 and a grant from the International Development Research Centre.     

Activation of particle associated rat liver guanine deaminase by lecithin and interferences of lecithin in protein precipitation

Summary Guanine deaminase solubilized from the light mitochondrial fraction of rat liver was activated by lecithin. The activation was proportional to the concentration of lecithin taken in the system. A ratio of 11 between the two constituents (protein and lecithin) was at least necessary for complete precipitation.Acknowledgment. The authors are grateful to Professor P.S.Krishnan, University of Calicut, Calicut, Kerala, for his interest.