Calcitonin: Effect on protein synthesis in different rat tissues

Summary Protein synthesis was inhibited in the pancreas whereas it was enhanced in the kidney and intestine (jejunumileum) after a single injection of porcine calcitonin (20 MRC units/kg b.wt). The incorporation of [³H]leucine into total protein in the brain, heart, liver and stomach did not change after the hormone treatment.Acknowledgment. This work has been achieved at the Institute of Medical Biochemistry, University of Aarhus, Aarhus, Denmark.     

Calcitonin in tissues of thyroidectomized monkey

Summary Immunochemical studies indicate that immunoreactive calcitonin (iCT) is present in many tissues of monkey following thyroidectomy (thx) (e.g. liver, thymus, lung). Extrathyroidal iCT may play a role in calcium metabolism.Supported by the Ella O. Latham Trust, George Washington, NCI Grant RO1CA22137-02, and the Veterans Administration.     

In vitro effects of different rat tissues on radioiodinated 4-iodoantipyrine

Résumé On a étudié l'action de differents tissus du rat sur la 4-iodoantipyrine radioiodée. On a observé une activité déiodante seulement avec le tissu hépatique.     

Converting enzyme content of different tissues of the rat

Résumé On a dosé l'enzyme de conversion dans différents tissus du rat au moyen d'une méthode chimique mesurant la libération d'histidyl-leucine à partir du substrat synthétique Z-phe-his-leu. Le poumon contient au moins 8 fois plus d'enzyme que tous les autres tissus étudiés. Il en contient notamment plus de 100 fois plus que le foie.     

Effect of nonprotein thiols on protein synthesis in isolated rat hepatocytes

The ability of nonprotein thiols to modulate rates of protein synthesis was investigated in isolated rat hepatocytes. Addition of cysteine stimulates protein labelling by [¹⁴C] Leucine. Glutahione depletion, induced by in vivod administration of L-buthionine sulfoximine and diethylmaleate, did not alter the effect of cysteine, although it decreased the rate of protein synthesis by 32%. The effect of cysteine on protein synthesis does not seem to be related to a perturbatin of the redox state of the NAD⁺/NADH system or to changes in the rate of gluconeogenic pathway. The following observations indicate that cysteine may stimulate protein syntheis by increasing intracellular levels of aspartate: 1. Amino-oxyacetate, an inhibitor of pyridoxyal-dependent enzymes, inhibits protein labelling and decreases aspartate cellular content, whereas most amino acids accumulate or remain unchanged; 2. Cysteine, in the absence or in the presence of amino-ocycetate, stimulates protein labelling and induces aspartate accumulation, although mot amino acids diminish or remain unchanged.     

Retardation of protein synthesis in rat tumours on inhibiting histamine formation

Zusammenfassung Untersuchung der Proteinsynthese bei Virustumoren. Anhand der Inkorporierungsgeschwindigkeit von¹⁴C-Leucin wurde festgestellt, dass die Hemmung der Proteinsynthese im Rous-Sarkom höher ist als im Walker-Karzinom.     

Calcitonin stimulation of pyrophosphatase activity in rat bone

Zusammenfassung Calcitonin als neues kalzium- und phosphor-senkendes Hormon wurde auf seine Wirkung auf die inorganische Pyrophosphataseaktivität von Knochen untersucht. Eine Steigerung der alkalinen Pyrophosphataseaktivität wurde vor der starken Senkung des Serum-Kalziums beobachtet.     

Time-dependence of estradiol effects on protein synthesis in the rat neurohypophysis.

The incorporation of 3H-leucine into neurohypophyseal proteins was measured in vitro, 24 h after the administration of a single dose of estradiol (0.3 mug) to castrated female rats. Estradiol treatment caused a significant increase of 3H-leucine incorporation into proteins of the posterior lobe. The effects of estradiol depended largely upon time injection. Rats injected at 06.00 h, i.e., at the end of the dark period exhibited a 74% increase in protein synthesis, whereas rat injected at 14.00 h, i.e., at the middle of the light period only showed a 30% of increase.     

Inhibitory effect of beta-ecdysone on protein synthesis by blowfly fat body in vitro

Synthesis of blow fly calliphorin and other blood proteins by larval fat body in organ culture is inhibited by beta-ecdysone. The findings suggest a novel function for the hormone.     

Inhibition of protein synthesis in ischaemic liver from phenobarbitone-treated rat.

Both ribosomal factors and cytosolic inhibitors are involved in the reduction of the rate of protein synthesis which occurs in the ischaemic hepatocyte from control and phenobarbitone-treated livers. Of these 2 factors it is the latter which seems to play a major role in determining the irreversible impairment of protein synthesis. Phenobarbitone administration has no effect on the rate of protein synthesis of ischaemic and post-ischaemic hepatocyte.