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Biomedical subjects

J Marek

Publications and source records attributed to J Marek.

At least 289 records · Page 16Linked to original sources
PubMed1975

Ultrastructural changes of the adrenal cortex in Cushing's syndrome treated with aminoglutethimide (Elipten Ciba)

The main ultrastructural feature of human adrenal cortices following administration of aminoglutethimide (Elipten CIBA), a steroid biosynthesis blocking agent, is a striking intracellular accumulation of lipids, also seen in the light microscopy. The lipids accumulate in the adrenocortical cells but are also stored in the cytoplasm of pericapillary histiocytes. The lipids are present in the adrenocortical cells mostly as rounded liposomes of variable size, whereas those in the histiocytes usually show up as an amorphous debris with abundant myelin figures and cholesterol crystals. In some areas of the adrenal cortex activated histiocytes changing into lipophages may become the prevalent cell. They also take the place of destroyed adrenocortical cells and can form compact cell aggregates of variable size or even columnar strands between neighbouring capillaries, thus resembling columns of adrenocortical cells. In some of the adrenocortical cells focal cytoplasmic degradation, turning into coagulation necrosis, was observed. In others initial cytolysis was found. In contrast with earlier findings in experimental animals, mitochondrial changes in humans were not a prominent feature. The only changes occasionally observed were a focal disappearance of the vesicular cristae and a concomitant fibrillary loosening of the mitochondrial matrix.

Adrenal Cortex↗
PubMed1975

Influence of age on orthostatic changes in plasma renin activity and urinary catecholamines in man.

The authors studied plasma renin activity (PRA), urinary epinephrine, norepinephrine and dopamine excretion and their mutual relationships in 54 healthy subjects under basal (recumbent) conditions and age-related orthostatic changes in these parameters. The test subjects were divided into six 10-years groups, according to their year of birth (1901-1910 to 1951-1960). In the oldest groups (1901-1910 and 1911-1920), both basal PRA values and norephrine and epinephrine excretion and their postural increase were smaller than in younger subjects. Conversely, urinary dopamine excretion and the dopamine/norepinephrine and epinephrine ratio rose with advancing age. There were no significant differences between the plasma sodium and potassium concentrations in the various groups. Urinary aldosterone excretion was slightly higher in the oldest group than in the others, but was still within the control value limits. The intravenous administration of Inderal reduced both resting PRA values and the orthostatic increase in the youngest age groups, so that their PRA approached the values in older subjects. Higher norepinephrine and epinephrine excretion and the lower dopamine/norepinephrine and epinephrine in young subjects may play a role in their higher PRA, especially in the orthostatic reaction. Diminution of sympathetic activity, with lower norepinephrine and epinephrine excretion and relatively high dopamine excretion, may have a direct bearing on the lower PRA values in older subjects. The diminished capacity of older subjects for catecholamine mobilization and raised renin secretion during an orthostatis stress may be related to the higher incidence of orthostatic forms of hypotension in old age.

Adult↗