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Biomedical subjects

G Mazzocchi

Publications and source records attributed to G Mazzocchi.

At least 217 records · Page 12Linked to original sources
PubMed1976

Investigations on the turnover of adrenocortical mitochondria. V. An autoradiographic study of the radioactivity decay in the mitochondrial compartment from the adrenal cortex of 3H-thymidine-injected rats.

The radioactivity decay of the mitochondrial compartment of 3H-thymidine-injected rats was followed by high resolution autoradiography. The number of days in which the radioactivity of the mitochondrial compartment is reduced to a half was calculated from the semilogarithmic plots of radioactivity versus time. Since DNA is a very stable molecule, it was assumed that this parameter can be an estimate of the half-life of adrenocortical mitochondria. It was found that the half-lives of mitochondria from the zonae glomerulosa, fasciculata and reticularis are, respectively, 8.20, 11.51 and 8.16 days.

Adrenal Cortex↗
PubMed1976

Investigations on the turnover of adrenocortical mitochondria. IV. A stereological study of the effect of chronic treatment with ACTH on the size and number of rat zona reticularis mitochondria.

The effects of chronic administration of of ACTH (up to 36 consecutive days) on the mitochondria of the zona reticularis of the rat adrenal cortex were investigated by stereologic techniques. It was found that ACTH induces two phases of hypertrophy of mitochondria alternating with two proliferative stages, which are associated with a significant decrease in the average volume of the organelles. It is suggested that, as in the zona fasciculata, ACTH controls the processes of growth and division of mitochondria in the zona reticularis. The mechanism underlying this action of ACTH as well as the differences between the responses to ACTH of the mitochondrial population of the two adrenal zones are discussed in the light of evidence indicating that mitochondria contain a complete genetic apparatus largely independent of nuclear control.

Adrenal Cortex↗
PubMed1976

Effect of ACTH on the zona reticularis of the rat adrenal cortex: an ultrastructural stereologic study.

The effects of ACTH on the rat adrenal zona reticularis were investigated by stereologic methods. It was found that the zona reticularis cell responsiveness to ACTH is similar to that of the zona fasciculata elements. This excludes that the zona reticularis of the adult rat can only function as the site of destruction of worn-out elements migrating from the adrenal outer zones.

Adrenal Cortex↗
PubMed1975

Investigations on the turnover of adrenocortical mitochondria. III. Stereologic and autoradiographic observations on the effect of chronic treatment with dexamethasone on the rat Zona fasciculata mitochondria.

The effects of chronic administration of dexamethasone (for up to 15 consecutive days) on both the morphology and DNA-synthesis of the mitochondria of the rat adrenal zona fasciculata were investigated by stereologic and autoradiographic techniques. Up to the 3rd day of continuous dexamethasone treatment, the average volume of mitochondria did not change, whereas the number of mitochondria per cell was significantly decreased. From the 3rd to the 15th day of hormonal administration both the volume and number of mitochondria were found to decrease in proportion to the duration of treatment. Autoradiography showed that after the 3rd day of dexamethasone administration there is virtually no incorporation of 3H-thymidine into the mitochondrial compartment. These findings are discussed in the light of evidence indicating that dexamethasone blocks ACTH-release by inhibiting the hypothalamo-hypophyseal axis. The results confirm the view that ACTH controls the maintenance of growth and proliferation of rat adrenocortical mitochondria.

Adrenal Cortex↗
PubMed1975

Effects of adenosine 3':5'-cyclic monophosphate and guanosine 3':5'-cyclic monophosphate on 3H-uridine incorporation into glomerulosal cells of hypophysectomized rat adrenal cortex.

The effects of cyclic AMP and cyclic GMP on the incorporation of 3H-uridine into glomerulosal cells of hypophysectomized rats were investigated by high resolution autoradiography. The quantitative analysis of autoradiographs shows that cyclic nucleotides, like ACTH, enhance the tracer incorporation into both nuclear and mitochondrial compartments. These findings are discussed in relation to previous results indicating that both cyclic nucleotides function as intracellular mediators of the trophic action of ACTH on the rat adrenal zona glomerulosa. The hypothesis that the mechanism of the glomerulotrophic action of ACTH and cyclic nucleotides involves the stimulation of nuclear and mitochondrial RNA synthesis is discussed.

Adrenal Cortex↗