Biomedical subjects

C Rossoni

Publications and source records attributed to C Rossoni.

17 recordsLinked to original sources

PubMed1992

Ornithine decarboxylase and ornithine decarboxylase-inhibiting activity in rat thymocytes.

Isolation of thymocytes from rat thymus resulted in the disappearance of the high activity of ornithine decarboxylase (ODC) that characterizes the thymus of young rats, together with the appearance of an antizyme-like ODC inhibiting activity, which showed a chromatographic profile that resembled that of dexamethasone-treated rat thymus. Omission of serum or addition of dexamethasone or spermidine did not affect appreciably the extent of the antizyme-like activity. On the other hand, a variety of hormonal effectors, i.e. insulin, glucagon, adrenalin and T3, as well as the phorbol ester, PMA or the mitogen, concanavalin A (Con A) induced ODC activity in cultured thymocytes together with the disappearance of the antizyme-like activity. A paradoxical, transient induction of ODC was caused by the transcriptional inhibitor, actinomycin D. Complexed ODC was detected in rat thymus, but not in thymocytes, either quiescent or stimulated by mitogens. These results indicate that thymic lymphocytes can express either ODC activity or its inhibitor depending on the hormonal and proliferative status of the cells.

Animals↗

PubMed1992

[Coenzyme Q9 biosynthesis in the aging myocardium after ischemia and reperfusion].

The purpose of the present study was to evaluate the biosynthesis of coenzyme Q9 (CoQ9) in isolated and perfused young (6 months) and aged (24 months) rat hearts, either under aerobic perfusion condition or during postischemic reperfusion. The young and aged hearts have been divided into 2 groups: Group A, aerobic perfusion for 60 min with recirculating Krebs-Henseleit solution, containing 0.8 microM p-OH-[U-14C]benzoate plus 2.5 mM mevalonlactone; Group B, severe ischemic perfusion for 30 min, followed by 60 min of reperfusion under the same experimental condition of Group A. At the end of the reperfusion the mitochondrial content of CoQ9 was lower in young than aged rat hearts (p < 0.01). In Group A the incorporation of the labeled precursor into mitochondrial CoQ9 was greater in the hearts of aged than young rats (p < 0.01); on the contrary, in Group B this incorporation was significantly reduced in aged than in young rats (p < 0.05). Thus, it is possible that, in the aged rat heart, the higher activity of CoQ9 biosynthesis is related to an elevated turnover of the coenzyme due to the aging process; moreover, this activity is partially reduced by an ischemic-reperfusion stress.

Aerobiosis↗

PubMed1992

Induction of ornithine decarboxylase by transcriptional inhibitors in quiescent thymocytes.

The transcriptional inhibitors actinomycin D and dichlororibofuranosylbenzimidazole induced ornithine decarboxylase activity in isolated, quiescent thymocytes, which otherwise did not show detectable levels of the enzyme. This paradoxical induction was transient and dependent on the presence of serum and continuous protein synthesis. However, alpha-amanitin, another inhibitor of transcription, did not affect ornithine decarboxylase activity. Dichlororibofuranosylbenzimidazole and actinomycin D were unable to enhance the activity of spermidine acetyltransferase or S-adenosyl-methionine decarboxylase, which are other inducible and short-lived enzymes involved in the metabolism of polyamines.

Animals↗

PubMed1987

Effects of dexamethasone on spermidine N1-acetyltransferase and ornithine activities in rat spleen.

Treatment of rats with the glucocorticoid dexamethasone causes an increase in the activity of cytosolic spermidine N1-acetyltransferase both in the spleen and thymus, but not, however, in liver, kidney or lung. The induced spermidine N1-acetyltransferase activity in the spleen catalyses acetylation of spermidine as well as spermine and sym-norspermidine, but not of diamines and histones. The enzyme induction depends on the dose of dexamethasone, and is suppressed by cycloheximide, which suggests that de novo protein synthesis is required for the action of this glucocorticoid. N1-acetylspermidine accumulates in the spleen after dexamethasone treatment, while spermidine progressively decreases and is partly converted into putrescine, the content of which transiently increases. In accordance with previous reports, dexamethasone was found to cause a rapid and large fall in the activity of spleen ornithine decarboxylase which was effected via the appearance of an inhibitor of the enzyme. Glucocorticoids exert large catabolic effects on lymphoid tissues, and further selectively affect the activities of spermidine N1-acetyltransferase and ornithine decarboxylase in the thymus and spleen. These latter selective responses may represent an important early event in lymphoid tissue response to glucocorticoid hormones.

Acetyltransferases↗

PubMed1986

Accumulation of N1-acetylspermidine in heart and spleen of isoprenaline-treated rats.

N1-Acetylspermidine is not detectable in rat heart, but its content greatly increases after a single injection of isoprenaline (10 mg/kg), reaching a concentration of about 10 nmol/g of tissue 4 h after the treatment. Part of the accumulated N1-acetylspermidine was split to putrescine. Isoprenaline also caused an increase of N1-acetylspermidine in the spleen, where its concentration increased 3.5-fold 6 h after the catecholamine. The accumulation of N1-acetylspermidine was dependent on the dose of isoprenaline in both the heart and the spleen, and was strongly inhibited by beta-antagonists and inhibitors of protein synthesis.

Animals↗

PubMed1986

Separation of N1- and N8-acetylspermidine isomers by reversed-phase column liquid chromatography after derivatization with dansyl chloride.

The separation of dansyl derivatives of N1- and N8-acetylspermidine by reversed-phase column liquid chromatography is reported. The influence of organic solvents on the retention of acetylspermidines was studied. Best resolutions were achieved using a C18 column and a ternary mobile phase composed of water, methanol and acetonitrile. The precolumn derivatization method permitted the detection of picomole quantities. A method for the determination of acetylspermidines in rat tissues is described.

Animals↗

PubMed1986

Effect of adrenergic stimulation on ornithine decarboxylase activity in the rat spleen.

The effect of a single administration of catecholamines on ornithine decarboxylase activity and polyamine biosynthesis in the rat spleen was investigated. Isoproterenol elicited a dose-dependent increase in spleen ODC activity which reached a maximum 4 hr after the administration of the drug. Putrescine content was also found to increase within a few hours, whereas S-adenosylmethionine decarboxylase activity and spermidine and spermine levels did not change significantly. Adrenaline and noradrenaline proved to be even more effective in increasing splenic ODC activity than isoproterenol. alpha- and beta-adrenergic antagonists prevented the ODC increase by catecholamines to a different extent.

Adenosylmethionine Decarboxylase↗

PubMed1986